Proposal

• Drop rendered documentation from the gh-pages branches to C driver versions older than any listed on https://repology.org/project/mongo-c-driver/versions, as these are unlikely to be referenced.
• Add a custom 404 page to link to current versions.

Background & Motivation

Updating analytics on all pages was a non-trivial effort in CDRIVER-6339. The rendered documentation for very old versions is unlikely to be useful.