doc: unify help text for "--edit" option This patch changes help text for "--edit" option of commands below: - fetch - qnew - qrefresh - qfold - commit - tag This unification reduces translation cost, too. This patch chooses not "further edit commit message already specified" (of "hg commit") but "invoke editor on commit messages" as unified help text for "--edit" option, because the latter is much older than the former.