Merge branch 'kh/bundle-docs'

Documentation for "git bundle" saw improvements to more prominently
call out the use of '--all' when creating bundles.

* kh/bundle-docs:
  Documentation/git-bundle.txt: discuss naïve backups
  Documentation/git-bundle.txt: mention --all in spec. refs
  Documentation/git-bundle.txt: remove old `--all` example
  Documentation/git-bundle.txt: mention full backup example