title: Versioned URLs: how can I tell search engines about more recent versions of the current page?
body: <p>I'll explain with a comparison of the hosted documentation for two projects: PostgreSQL and Django. The PostgreSQL project has documentation which follows the schema <code>http://www.postgresql.org/docs/&lt;MAJOR&gt;.&lt;MINOR&gt;</code>, while the Django project has documentation which follows the URL schema <code>https://docs.djangoproject.com/en/&lt;MAJOR&gt;.&lt;MINOR&gt;</code>. Google, however, treats these projects very differently: when searching Google for "Django foobar", the results all link to the most recent version, as is probably desired; but when searching Google for "Postgres foobar", the results link to an ad hoc variety of different versions, some of which are very old.</p>
  
  <p>It seems like the Django project has some technique for informing Google of the most recent documentation. However, I don't know what this technique could be. I would like to know in order to host my own versioned documentation.</p>