Merge branch 'patch-1' into 'master'

Update installation.md to Ruby 2.6.1 to fix https://github.com/tootsuite/mastodon/issues/10105

See merge request !27
2 jobs from master in 17 seconds (queued for 8 seconds)
Status Job ID Name Coverage
  Test
passed #1456
pages

00:17

 
  Deploy
passed pages:deploy

00:00