add redirect for github-free-for-teams (second attempt)
NOTE: second attempt at this MR, the first one was having issues with merge trains.
Add redirect for github-free-for-teams from https://about.gitlab.com/blog/2020-04-14-github-free-for-teams to https://about.gitlab.com/blog/2020/04/14/github-free-for-teams/
relates #7155 (closed)