crecord: rewrite help string to avoid mentioning "crecord"
Despite its heritage, "crecord" is now mostly Mercurial-internal
jargon. I find it better to call it "the curses hunk selector".
Also slightly rewrote the part about which commands can use it. While
I do believe that commit, shelve, and revert are the only commands in
core that can use it, Evolve also adds at least amend and uncommit to
the list.