Attempts to fix the content negotiation caching issue #134.

Remove caching from pages ending with a / which MAY (or may not, more
likely) help in resolving issue #134.

Update the list of mobile user agents.

The theory is that nowadays most themes are responsive, so there's
no need for custom "mobile detection" logic anymore. Try to validate
the theory starting with Android devices.

Specifically fix the cached files path.

According to the docs in
https://httpd.apache.org/docs/current/rewrite/flags.html#flag_l using
[L] in an .htaccess context incurs the risk of infinite recursion,
which is exactly what we were seeing in production for non-existing
.php files. Use [END] instead.

Update the WP Multisite section according to
https://wordpress.org/support/article/htaccess/#wordpress-3-5-and-up

Merges the contents of ai3/docker/noblogs (composer branch).