commands: tweak help for 'heads'.
- prefer "changeset" over "revision" for internal consistency
- clarify explanation of branch heads
- add a line break
- tighten some wording
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.