WP_Object_Cache writeup, missing plugin mention

[OllieJones]

See ​https://developer.wordpress.org/reference/classes/wp_object_cache/#persistent-cache-plugins

It mentions several object cache plugins, including mine, but does not mention ​https://wordpress.org/plugins/docket-cache/ .

Maybe a bullet item can be added saying:

• [Docket Cache - Object Cache Accelerator](​https://wordpress.org/plugins/docket-cache/) uses php's built-in opcode cache mechanism to provide a persistent object cache.

[dd32]

The page isn't intended on mentioning every object cache drop-in available IMHO, but probably worthwhile mentioning any plugin with > x installs.

Perhaps it could be expanded with a link to ​https://wordpress.org/plugins/tags/object-cache/ for "other plugins" too.

[dd32]

I've added Docket cache, clarified that the memcache extension is needed for the memcache dropin, and added memcache redux which uses the previously mentioned memcacheD extension.