introduce install docs Fix double database creation in `openstack.osa.db_setup. Remove `grafana-piechart-panel` as it is built into Grafana since v8.0. Add and refresh installation documentation. Change-Id: I046cead13f02f2ae5a975b6a6eeaae818cbf5757 Signed-off-by: Dmitriy Chubinidze <dcu995@gmail.com> Co-Authored-By: Dmitriy Rabotyagov <noonedeadpunk@gmail.com>