I've noticed that the documentation search on the site is currently in a poor state.
Previously, when looking at the documentation for a specific version (like https://web.archive.org/web/20170905162419/https://www.postgresql.org/docs/9.5/static/index.html ), searching for terms in the search box would take you to a filtered view for that version (with a "u" search parameter set to "/docs/$VERSION/", with version values like "9.5", "11", "current", and "dev" supported. This no longer works at all, and the experience of searching the documentation right now is consequently very poor.
Both of these issues (searches no longer automatically filter for the currently viewed version, and current documentation is not indexed) are serious regressions in the usability of the site.