The Organiser Tips page on the groups portal was sadly
almost blank. This patch brings all the content from the wiki
(https://wiki.openstack.org/wiki/OpenStackUserGroups/HowTo )
and modernises it.
Also a new section started aimed at people who aren't group
organisers but want to know what a user group is.
Change-Id: I526f29c0e89158298b90cc875864a819b00e6ba6