This complements the changes done in the last commit, and also fixes the
`glg` output, and removes the now unnecessary `--date=relative`
parameter from `glG`.
Although I insisted on the `--long-option` format on 8669a4f, I think
`rm -rf` is pretty common and recognizable, so revert to that.
Add missing aliases to README.md, and improve description of existing
ones. The main improvement is trying to be more concise, so instead of
repeating "records changes to the repository" multiple times, simply say
"commits", for example. Also try to use words that match the alias
letters, so for "gcs" say "shows" instead of "displays", for example.
c501a1b64c