Crosslinks out to web editor page

For users who need this level of help, we should tell them how to
upload a file.

doc/user/project/merge_requests/creating_merge_requests.md

@@ -82,7 +82,7 @@ merge request is merged.
 
 You can create a merge request when you add, edit, or upload a file to a repository.
 
-1. Add, edit, or upload a file to the repository.
+1. [Add, edit, or upload](../repository/web_editor.md) a file to the repository.
 1. In the **Commit message**, enter a reason for the commit.
 1. Select the **Target branch** or create a new branch by typing the name (without spaces, capital letters, or special chars).
 1. Select the **Start a new merge request with these changes** checkbox or toggle. This checkbox or toggle is visible only