hghave: document format for version feature checks as <name><vers>, no dots
I had a bit of a difficult time when attempting to fix a use of `py-38` when
trying to figure out what the correct way of specifying the feature was. By
having the strings 'py-3*' and 'py3.8' in the hghave.checkvers docstring, I
would have had a much easier time of it instead of having to trace exactly what
was happening here.
Differential Revision: https://phab.mercurial-scm.org/D7023
https://bz.mercurial-scm.org/1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..