lib/repo: Add gtk-doc comment to OstreeRepoCommitState
lib/repo: Add gtk-doc comment to OstreeRepoCommitState

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Closes: #1335
Approved by: cgwalters

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree