add links to documentation for new features

RELEASE-NOTES.md

@@ -22,7 +22,7 @@ $ git -C forgejo log --oneline --no-merges origin/v1.20/forgejo..origin/v1.21/fo
   will be portable from one version to another (even a patch version).
   - [Restrict certificate type for builtin SSH server](https://codeberg.org/forgejo/forgejo/pulls/1172). This is a breaking change for setups where the builtin SSH server is being used and for some reason host certificates were being used for authentication.
   - [Some Forgejo CLI options have changed](https://codeberg.org/forgejo/forgejo/commit/d0dbe52e76f3038777c3b50066e3636105387ca3) and scripts may need to be updated. For instance `--verbose` is no longer a global option and is implemented on a per sub-command basis. Check `forgejo --help` or `forgejo docs` for more information.
-  - [Remove "CHARSET" config option for MySQL and always use "utf8mb4"](https://codeberg.org/forgejo/forgejo/commit/ce46834b938eb687152a680669ada95a26304178). It has been a requirement for years and specifying anything else is likely to cause issues.
+  - [Remove "CHARSET" config option for MySQL and always use "utf8mb4"](https://codeberg.org/forgejo/forgejo/commit/ce46834b938eb687152a680669ada95a26304178). It has been a requirement for years and specifying anything else is likely to cause issues. Existing MySQL databases still using `utf8` can be converted using the CLI: `forgejo doctor convert`.
   - [Set SSH_AUTHORIZED_KEYS_BACKUP to false by default](https://codeberg.org/forgejo/forgejo/commit/469d89b95a1ce18dd34808a95c7230375e828e24). There is no automatic cleanup of these backups and can end up using a significant amount of disk space over time.
   - [The minimum RSA keylength is now 3072 instead of 2048](https://codeberg.org/forgejo/forgejo/commit/c533991519816313dfaa0ddcec183756a97b9348).
 - **Forgejo Actions:**
@@ -58,22 +58,23 @@ $ git -C forgejo log --oneline --no-merges origin/v1.20/forgejo..origin/v1.21/fo
     - WDL: [broadinstitute/wdl-sublime-syntax-highlighter](https://github.com/broadinstitute/wdl-sublime-syntax-highlighter)
     - WGSL: [wgsl-analyzer/wgsl-analyzer](https://github.com/wgsl-analyzer/wgsl-analyzer)
     - WebAssembly Interface Type: [bytecodealliance/vscode-wit](https://github.com/bytecodealliance/vscode-wit)
-  - [Newly pushed branches show in the web UI with a link to create a PR](https://codeberg.org/forgejo/forgejo/commit/6375419468edc95fdfac94aac3b0e10b23743557).
-  - Labels that are no longer useful [can be archived](https://codeberg.org/forgejo/forgejo/commit/cafce3b4b5afb3f254a48e87f1516d7b5dc209b6). They can no longer be selected but they remain on existing issues.
+  - [Newly pushed branches show in the web UI with a link to create a PR](https://codeberg.org/forgejo/forgejo/commit/6375419468edc95fdfac94aac3b0e10b23743557). Read more [about the `New Pull Request` button](https://forgejo.org/docs/v1.21/user/pull-requests-and-git-flow/#create-a-pull-request).
+  - Labels that are no longer useful [can be archived](https://codeberg.org/forgejo/forgejo/commit/cafce3b4b5afb3f254a48e87f1516d7b5dc209b6). They can no longer be selected but they remain on existing issues. Read more [about archiving labels](https://forgejo.org/docs/v1.21/user/labels/#archiving-labels).
   - The blame view now [takes into account](https://codeberg.org/forgejo/forgejo/commit/ed64f1c2b835bf9332bf8347be9675ef29c8274b) the [`.git-blame-ignore-revs`](https://git-scm.com/docs/git-config#Documentation/git-config.txt-blameignoreRevsFile) file.
-  - [Pre-register OAuth2 applications for git credential helpers](https://codeberg.org/forgejo/forgejo/commit/63ab92d7971e4931e98f014f2c5385d2242fa780).
+  - [Pre-register OAuth2 applications for git credential helpers](https://codeberg.org/forgejo/forgejo/commit/63ab92d7971e4931e98f014f2c5385d2242fa780). Read more in the git authentication section of the [user guide](https://forgejo.org/docs/v1.21/user/oauth2-provider/#git-authentication) and the [administrator guide](https://forgejo.org/docs/v1.21/admin/oauth2-provider/#git-authentication).
   - Admins can be [notified via email](https://codeberg.org/forgejo/forgejo/commit/7d2d9970115c94954dacb45684f9e3c16117ebfe) when a new user registers to help fight spam bots.
   - Packages [can be configured to redirect requests to the S3 server](https://codeberg.org/forgejo/forgejo/commit/c890454769562e0ec2978e123aaf3d9a43e5ef4f) for clients that support this feature.
-  - When a PR contains multiple commits, it is now possible [review to each commit independently](https://codeberg.org/forgejo/forgejo/commit/55532061c83d38d33ef48bdc5eeac0f652844e8a).
+  - When a PR contains multiple commits, it is now possible [review to each commit independently](https://codeberg.org/forgejo/forgejo/commit/55532061c83d38d33ef48bdc5eeac0f652844e8a). Read more [about selecting commits for review](https://forgejo.org/docs/v1.21/user/pull-requests-and-git-flow/#reviews).
   - Issues can [be deleted in batch](https://codeberg.org/forgejo/forgejo/commit/a1c5057fe81c25dfd1777e9625eb5480c45897ea).
   - An email can be associated with [an Organisations](https://codeberg.org/forgejo/forgejo/commit/6598d0291cf7dfeb00cb5e5d18faf2bf46fad596).
-  - The CODEOWNERS file is [interpreted to automatically set reviewers on PRs](https://codeberg.org/forgejo/forgejo/commit/3bdd48016f659c440d6e8bb57386fab7ad7b357b).
+  - The CODEOWNERS file is [interpreted to automatically set reviewers on PRs](https://codeberg.org/forgejo/forgejo/commit/3bdd48016f659c440d6e8bb57386fab7ad7b357b). The CODEOWNERS file is loaded from these paths in this order: `./CODEOWNERS`, `./docs/CODEOWNERS`.
   - Issue search [were reworked entirely](https://codeberg.org/forgejo/forgejo/commit/1e76a824bcd71acd59cdfb2c4547806bc34b3d86) to fix the shortcomings of the previous implementation.
   - [Allow "latest" to be used as a release tag when downloading a file](https://codeberg.org/forgejo/forgejo/commit/a7d9a70552410d797cefc87b177b33ca4a1a60c4).
   - [Authentication via reverse proxy is available and disabled by default](https://codeberg.org/forgejo/forgejo/commit/e97e883ad50774f249c8c694598c25a17227299b).
   - [Add API for changing avatars](https://codeberg.org/forgejo/forgejo/commit/254a82842addb1475611789107c3720e37394879).
 - **User Interface:**
   - [Show OpenID Connect and OAuth on the signup page](https://codeberg.org/forgejo/forgejo/commit/63b53af933d748f9b4e0f1273e3701b4c3d08ac3).
+  - [Show branches and tags that contain the commit being displayed](https://codeberg.org/forgejo/forgejo/commit/bd6ef718548767ff209048eb8443a067106908bf)
   - [Add 'Show on a map' button to the location in the usr profile](https://codeberg.org/forgejo/forgejo/commit/d58c5425799335ea57f27461f99ddd1078e9b2de).
   - [Render plaintext task list items for markdown files](https://codeberg.org/forgejo/forgejo/commit/eaea530d6bc84b23e6ff14ff8c2a74aa3b67ecd0).
   - The administrators user details page [was modified](https://codeberg.org/forgejo/forgejo/commit/5b5bb8d3546e6504b689b01d3ac4897dda3aee3d).
@@ -88,6 +89,7 @@ $ git -C forgejo log --oneline --no-merges origin/v1.20/forgejo..origin/v1.21/fo
   - It is no longer possible to [change the run user in the installation page](https://codeberg.org/forgejo/forgejo/commit/d17a848fe275c3e8734a4dfcaf2eae8ca0dc361c).
   - [Update emoji set](https://codeberg.org/forgejo/forgejo/commit/e882398c5acb99db555553acc2da89db73713710)  to [Unicode 15](https://unicode.org/versions/Unicode15.0.0/).
   - [Improve the image Diff user interface](https://codeberg.org/forgejo/forgejo/commit/09faf43ef822ca4dbdfb2a2714ad43a782acf6e8).
+  - [Rebuilding the issue index from the cron task list in the admin panel](https://codeberg.org/forgejo/forgejo/commit/47fddaadc8b4c8d4d4359d6209b9fe06d6387a30).
 * **Enhancements:**
   - [Improve the privacy of the user profile settings](https://codeberg.org/forgejo/forgejo/commit/ff90c87c878b03e7beabac5f19396e0db2c25a1e).
   - [Add the upload URL to the release API](https://codeberg.org/forgejo/forgejo/commit/a9ce570298d4541bc1b5598dc080d9e4541de17b).