Migrate versions tree

[garazdawi]

We have all the information available to create https://erlang.org/download/otp_versions_tree.html when generating erlang.org, so we might as well use that and put some bootstrap styling on it.

An idea I had was to also add a filter where you can search for things such as:

• "inets" and get all versions that contain inets changes
• "inets-1.2.3" and the version that contains that inets version
• "OTP-123" and get all versions that contain that ticket
• "Fix documentation flattening for ExDoc #123" and get all versions that contain that issue