Add contributing guide and license

See https://gitlab.com/gitlab-com/organization/issues/146
2 jobs for update-contributing-and-license in 2 minutes and 25 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Build
passed #40205475
docker shared
build

00:01:39

 
  Test
passed #40205476
docker shared
test

00:00:46