This question/proposal relates to well-known problem:
How I can embed CI badge for the current branch?

I tried solve it for my projects and I don't see an acceptable solution.
Current options lent to one of the two things:

1. You have to hardcode different branche names in different branches and have a pain on every merge.
2. You report status for fixed number of branches in a table. Then you don't have badges for short-living branches (like feature branches in gitflow).

Acceptable solution can be done, if we tweak github markdown processing, for instance during autolinking, since it's very close spiritually. :)