While https://developer.blender.org doesn't display a prominent readme,
other 3rd party hosting services do (github/gitlab/bitbucket).
People may stumble on these sites (searching `blender git` here, 2 of the top 4 results link to github for eg),
even ignoring this - having a readme in Blender's root directory can be generally useful too.
Suggested text (taken from blender.org, roughly following https://github.com/KDE/krita as a template).
{P951}
Screenshot from github: {F6939114}