Document new merge and delegate commands from triagebot

src/SUMMARY.md

@@ -32,6 +32,7 @@
     - [Lock](./triagebot/lock.md)
     - [Major Changes](./triagebot/major-changes.md)
     - [Mentions](./triagebot/mentions.md)
+    - [Merge](./triagebot/merge.md)
     - [Merge Conflicts](./triagebot/merge-conflicts.md)
     - [No Merge Policy](./triagebot/no-merge.md)
     - [Nominate](./triagebot/nominate.md)

src/triagebot/merge.md

@@ -0,0 +1,69 @@
+# Merge 
+
+The `merge` feature enables merging (and delegating the rights) to merge a PR in repositories that use the merge queue.
+
+> Note: it currently does not work for repositories using bors or using direct PR merging, without a merge queue.
+
+## Usage
+
+### Merge
+
+To merge a pull request, any authorized users (see below) may enter the command:
+
+```text
+@rustbot merge
+```
+
+This will enqueue the PR in the merge queue.
+
+The command is only available for:
+ - members with at least write permissions on the repository
+ - users who have been delegated the rights to merge
+
+### Delegation
+
+#### Delegate to the author
+
+To delegate the rights to merge the pull request to the PR author, any members with at least write permissions on
+the repository may enter the command:
+
+```text
+@rustbot delegate+
+```
+
+or
+
+```text
+@rustbot delegate
+```
+
+and will post a message roughtly like this:
+
+> :v: @User, you can now merge this pull request!
+>
+> If @reviewer told you to merge after making some further change, then please make that change and post `@rustbot merge`.
+
+#### Delegate to a specific user
+
+To delegate to another user, rather than the PR author, it's possible to specify a specific user:
+
+```text
+@rustbot delegate=@other_user
+```
+
+## Configuration
+
+This feature is enabled on a repository by having a `[merge]` table in `triagebot.toml`:
+
+```toml
+[merge]
+type = "merge-queue"
+```
+
+There are several optional keys that you can include:
+
+- `type` --- what type of merging should be used, supported: `merge-queue`.
+
+## Implementation
+
+See [`src/handlers/merge.rs`](https://github.com/rust-lang/triagebot/blob/HEAD/src/handlers/merge.rs).