Add documentation header to all our `bin/` utilities + auto-generate overall doc

[AliSoftware]

Internal ref: p1729815426023749/1729802878.523709-slack-CC7L49W13

To better document all of the utilities we make available via this plugin, we should adopt the convention of adding some documentation lines at the start of each script.

• comment_on_pr is an example of a good citizen that could be use as inspiration / starting point
• I have recently added .cursorrules via Introduce basic .cursorrules for this repo #154 that can help writing and enforcing those documentation.

As a bonus, we could also have a script that take all the bin/* scripts in the plugin, extracts the doc header, and generates a README from it

• We could then maybe have a Danger check that runs the script on CI and warns if it doesn't match the current README checked out in the repo, suggesting the PR author to run the script locally themselves and commit the changes
• (we could also consider to have the CI push the generated README itself instead of asking the PR author to push it, but in general I'm not super keen to have CI push commits if we can avoid it)