Fix ratbag-command manpage
Fix ratbag-command manpage

* Description capitalisation
* Grammar
* Hyphen encoding
* --version

Signed-off-by: Stephen Kitt <9ce5770b3bb4b2a1d59be2d97e34379cd192299f@sk2.org>

whot/libratbag,whot/libratbag,libratbag/libratbag,libratbag/libratbag,whot/libratbag,libratbag/libratbag