In my project, we have different versions of the documentation for the git head and the latest stable release. Users currently must clone our repo and checkout the develop branch to read anything that isnt in master.
I have documented my workaround here: https://momi.ca/posts/2021-10-29-multipleSourcehutMan.html
This is indeed a rather cumbersome workaround. I think ideally the repo owner should be able to select on man.sr.ht which git refs (i.e. branches or tags) he/she wants to render, and which is the default. The user should be able to switch between the various versions of the documentation , and optionally a clear notice should be shown if the user is not on the latest version.