Minor API.md changes (#1351)

docs/Using-the-API/API.md

@@ -30,7 +30,7 @@ API overview
   - [Instance](#instance)
   - [Mention](#mention)
   - [Notification](#notification)
-  - [Relationships](#relationships)
+  - [Relationships](#relationship)
   - [Results](#results)
   - [Status](#status)
   - [Tag](#tag)
@@ -467,7 +467,7 @@ ___
 | `acct`                   | Equals `username` for local users, includes `@domain` for remote ones |
 | `id`                     | Account ID |
 
-### Notifications
+### Notification
 
 | Attribute                | Description |
 | ------------------------ | ----------- |
@@ -475,9 +475,9 @@ ___
 | `type`                   | One of: "mention", "reblog", "favourite", "follow" |
 | `created_at`             | The time the notification was created |
 | `account`                | The [Account](#account) sending the notification to the user |
-| `status`                 | The [Status](#status) associated with the notification, if applicible |
+| `status`                 | The [Status](#status) associated with the notification, if applicable |
 
-### Relationships
+### Relationship
 
 | Attribute                | Description |
 | ------------------------ | ----------- |