Merge branch 'docs-wip-refactor' into 'master'

Docs: Rewrite Work In Progress MR page

Closes #34559

See merge request gitlab-org/gitlab-ce!25732

doc/user/project/merge_requests/work_in_progress_merge_requests.md

 # "Work In Progress" Merge Requests
 
-To prevent merge requests from accidentally being accepted before they're
-completely ready, GitLab blocks the "Accept" button for merge requests that
-have been marked a **Work In Progress**.
+If a merge request is not yet ready to be merged, perhaps due to continued development
+or open discussions, you can prevent it from being accepted before it's ready by flagging
+it as a **Work In Progress**. This will disable the "Merge" button, preventing it from
+being merged, and it will stay disabled until the "WIP" flag has been removed.
 
 ![Blocked Accept Button](img/wip_blocked_accept_button.png)
 
-To mark a merge request a Work In Progress, simply start its title with `[WIP]`
-or `WIP:`. As an alternative, you're also able to do it by sending a commit
-with its title starting with `wip` or `WIP` to the merge request's source branch.
-
-![Mark as WIP](img/wip_mark_as_wip.png)
-
-To allow a Work In Progress merge request to be accepted again when it's ready,
-simply remove the `WIP` prefix.
-
-![Unmark as WIP](img/wip_unmark_as_wip.png)
-
-## Filtering merge requests with WIP Status
-
-To filter merge requests with the `WIP` status, you can type `wip`
-and select the value for your filter from the merge request search input.
+## Adding the "Work In Progress" flag to a Merge Request
+
+There are several ways to flag a merge request as a Work In Progress:
+
+- Add "[WIP]" or "WIP:" to the start of the merge request's title. Clicking on
+  **Start the title with WIP:**, under the title box, when editing the merge request's
+  description will have the same effect.
+- Add the `/wip` [quick action](../quick_actions.md#quick-actions-for-issues-and-merge-requests)
+  in a discussion comment in the merge request. This is a toggle, and can be repeated
+  to change the status back. Note that any other text in the comment will be discarded.
+- Add "wip" or "WIP" to the start of a commit message targeting the merge request's
+  source branch. This is not a toggle, and doing it again in another commit will have
+  no effect.
+
+## Removing the "Work In Progress" flag from a Merge Request
+
+Similar to above, when a Merge Request is ready to be merged, you can remove the
+"Work in Progress" flag in several ways:
+
+- Remove "[WIP]" or "WIP:" from the start of the merge request's title. Clicking on
+  **Remove the WIP: prefix from the title**, under the title box, when editing the merge
+  request's description, will have the same effect.
+- Add the `/wip` [quick action](../quick_actions.md#quick-actions-for-issues-and-merge-requests)
+  in a discussion comment in the merge request. This is a toggle, and can be repeated
+  to change the status back. Note that any other text in the comment will be discarded.
+- Click on the **Resolve WIP status** button near the bottom of the merge request description,
+  next to the "Merge" button (see [image above](#work-in-progress-merge-requests)).
+  Must have at least Developer level permissions on the project for the button to
+  be visible.
+
+## Including/Excluding WIP Merge Requests when searching
+
+When viewing/searching the merge requests list, you can choose to include or exclude
+WIP merge requests by adding a "WIP" filter in the search box, and choosing "Yes"
+(to include) or "No" (to exclude).
 
 ![Filter WIP MRs](img/filter_wip_merge_requests.png)