The command's help text says "Abandon a revision", which I think is a
good indication that the command's name should be `abandon`. This
patch renames the command and other user-facing occurrences of the
word. The remaining occurrences should be removed when I remove
support for evolution.
With this commit, you can run `jj concepts branches` to get help about
the "branches" concept. We don't have much help for other commands and
their arguments yet, but I'm starting with concept guides so we can
point to them as we add help for commands and their arguments.
I initially tried to make the command to get help be `jj help
--concept branches`. That would require replacing clap's
implementation of the help command with our own. clap-rs/clap#1350
prevented me from doing that. But I'm pretty happy with having it
under `jj concepts` anyway. It's probably more discoverable that way.
I tried to mimic clap's styling with yellow headings.
Now that our own branches and tags are updated when git refs are
updated and the user can use them to specify revisions, we can start
displaying them instead of the git refs. This commit adds new
`branches` and `tags` template keywords and updates the default
templates to use them instead of `git_refs`.
