Can the website documentation be updated to support documentation per release with a version selector?

I just had a case where my teammate wanted to use the ContainMatch (#1138) because he found it on the website. But could not, even though we're on 5.9.0. Ofcourse I know by looking in the repo that it's not released yet, but for some people it can be confusing because the documentation is ahead.

Originally posted by @WingTai in #814