docs: Update commit signing instructions in RELEASE.md
This brings the release process in-line with the latest changes to https://wiki.gnome.org/MaintainersCorner/Releasing.
Signed-off-by: Philip Withnall pwithnall@endlessos.org
This brings the release process in-line with the latest changes to https://wiki.gnome.org/MaintainersCorner/Releasing.
Signed-off-by: Philip Withnall pwithnall@endlessos.org