Create better doc format for MR merge widget map
Problem
In #299193 (closed) we documented the states, actions, and information of the MR merge widget, using just an outline and screenshots.
However, we need a format that is not only easy to consume by anyone, but also easy to maintain by anyone, so that this documentation can evolve with the product. For example, the working group described in #300042 (closed) could benefit (and contribute) to this documentation.
Solution
Creating a visual for it (a flowchart diagram or similar) might be a good option. Mermaid graphs are one option for that. As inspiration, see Slack's notification trigger flowchart.
The location for this documentation is also up for consideration. Both Pajamas or the user docs are commonly used for “building the product” documentation, although Pajamas is solely focused on that and the user docs are, well, for “how to use the product.”