doc: Fix fix "Not(e) that you can(not) abbreviate".

The commands --help, --version, --dump-options are special in that
they can't be abbreciated on the command line. This is to avoid
problems with regular options with the same prefix.

• Fixes-commit: 0a27d8a57c4c990fcada4278a1ce2e6fc9043e9
• Signed-off-by: Werner Koch <wk@gnupg.org>