Fix markdown rendering

What does this MR do and why?

This MR changes the README file only.

It fixes the markdown rendering for 2 of the examples. These were rendered slightly broken within GitLab itself, and completely broken on rubydoc (see https://www.rubydoc.info/gems/gitlab-triage#summary-policies).

Screenshots - GitLab UI

Notice the first - [ ] inside the example wasn't rendered.

Before	After

Screenshots - rubydoc

Notice the rendering is broken once the example description start. This also makes some sub-headings not recognized, and therefore missing from the table of contents.

I have no idea how to test that this change will in fact fix the issue in rubydoc as well. Hope for the best?

Edit: after releasing this change as part of 1.41.0 (!294 (merged)), we can confirm the rendering is fixed 🎉

Before	After