readme: remove the part about 3.7 and hgext3rd
We are using direct path already so we don't need any magic here. The
'hgext3rd.'bit is only required (for 3.7) when the module is installed and we
rely on sys.path to find it.
# topics
Topics are an experiment to see if maybe the workflow defined by git
branches and hg bookmarks is only partially what users want - perhaps
something that feels more like a traditional VCS branch is right, but
that it should "dissolve" upon being finished. This extension exists
to be a sandbox for that experimentation.
# usage
Enable topics like any mercurial extension: download the source code to a
local directory, and add that directory to your `.hgrc`:
[extensions]
topics=path/to/hg-topics/src