Trivial docs annoyance: current <-> 10 - Mailing list pgsql-www

It's a tiny thing, but there's no longer any obvious way to get from
https://www.postgresql.org/docs/10/static/index.htmlto https://www.postgresql.org/docs/current/static/index.html or
viceversa without going via another version of the docs or manually editing the URL. 

Cheers,
  Steve