docs/blueprints: Fix list formating

List didn't display fine, if not prefixed by empty line.

Relate-to: https://allscenarios.readthedocs.io/en/latest/meta-ohos/blueprints/touchpanel.html
Forwarded: https://git.ostc-eu.org/OSTC/OHOS/meta-ohos/-/merge_requests/226


Signed-off-by: Philippe Coval <rzr@users.sf.net>