Update allow-collaboration page, minor cleanup

doc/user/project/merge_requests/allow_collaboration.md

@@ -24,19 +24,17 @@ of the merge request.
 ## Enabling commit edits from upstream members
 
 In [GitLab 13.7 and later](https://gitlab.com/gitlab-org/gitlab/-/issues/23308),
-this setting is enabled by default. It can be changed by users with Developer
-permissions to the source project. Once enabled, upstream members can
-retry the pipelines and jobs of the merge request:
+this setting is enabled by default. It can be changed by users with the
+Developer [role](../../permissions.md) for the source project. After it's enabled,
+upstream members can retry the pipelines and jobs of the merge request:
 
-1. While creating or editing a merge request, select the checkbox **Allow
-   commits from members who can merge to the target branch**.
+1. While creating or editing a merge request, scroll to **Contribution** and
+   then select the **Allow commits from members who can merge to the target branch**.
+   checkbox.
+1. Finish creating your merge request.
 
-   ![Enable contribution](img/allow_collaboration.png)
-
-1. Once the merge request is created, you can see that commits from members who
-   can merge to the target branch are allowed.
-
-   ![Check that contribution is enabled](img/allow_collaboration_after_save.png)
+After you create the merge request, the merge request widget displays a message:
+**Members who can merge are allowed to add commits.**
 
 ## Pushing to the fork as the upstream member
 
@@ -48,41 +46,39 @@ Assuming that:
 - The forked project URL is `git@gitlab.com:thedude/awesome-project.git`.
 - The branch of the merge request is `update-docs`.
 
-Here's how the process would look like:
-
-1. First, you need to get the changes that the merge request has introduced.
-   Click the **Check out branch** button that has some pre-populated
-   commands that you can run.
-
-   ![Check out branch button](img/checkout_button.png)
+To find and work with the changes from the fork:
 
-1. Use the copy button to copy the first command and paste them
-   in your terminal:
+1. Open the merge request page, and select the **Overview** tab.
+1. Scroll to the merge request widget, and select **Check out branch**:
+   ![Check out branch button](img/commit-button_v13_12.png)
+1. In the modal window, select **{copy-to-clipboard}** (**Copy**) for step 1
+   to copy the `git fetch` and `git checkout` instructions to your clipboard.
+   Paste the commands (which look like this example) into your terminal:
 
    ```shell
    git fetch git@gitlab.com:thedude/awesome-project.git update-docs
    git checkout -b thedude-awesome-project-update-docs FETCH_HEAD
    ```
 
-   This fetches the branch of the forked project and then create a local branch
+   These commands fetch the branch from the forked project, and create a local branch
    based off the fetched branch.
 
-1. Make any changes you want and commit.
-1. Push to the forked project:
+1. Make your changes to the local copy of the branch, and then commit them.
+1. In your terminal, push your local changes back up to the forked project. This
+   command pushes the local branch `thedude-awesome-project-update-docs` to the
+   `update-docs` branch of the `git@gitlab.com:thedude/awesome-project.git` repository:
 
    ```shell
    git push git@gitlab.com:thedude/awesome-project.git thedude-awesome-project-update-docs:update-docs
    ```
 
-   Note the colon (`:`) between the two branches. The above command pushes the
-   local branch `thedude-awesome-project-update-docs` to the
-   `update-docs` branch of the `git@gitlab.com:thedude/awesome-project.git` repository.
+   Note the colon (`:`) between the two branches.
 
 ## Troubleshooting
 
 ### Pipeline status unavailable from MR page of forked project
 
-When a user forks a project, the permissions on the forked copy are not copied over
+When a user forks a project, the permissions of the forked copy are not copied
 from the original project. The creator of the fork must grant permissions to the
 forked copy before members in the upstream project can view or merge the changes
 in the merge request.