Merge branch 'rr/shortlog-doc'

Update documentation for "log" and "shortlog".

* rr/shortlog-doc:
  builtin/shortlog.c: make usage string consistent with log
  builtin/log.c: make usage string consistent with doc
  git-shortlog.txt: make SYNOPSIS match log, update OPTIONS
  git-log.txt: rewrite note on why "--" may be required
  git-log.txt: generalize <since>..<until>
  git-log.txt: order OPTIONS properly; move <since>..<until>
  revisions.txt: clarify the .. and ... syntax
  git-shortlog.txt: remove (-h|--help) from OPTIONS

diff --cc Documentation/revisions.txt
Simple merge

diff --cc builtin/log.c
Simple merge