Wiki still mentions `CachedWorld` table

[jonathanhefner]

The spec for the Caching test in the wiki mentions a CachedWorld table. However, that table is not actually defined (see the PostgreSQL schema and MySQL schema), and is a point of confusion when implementing the test for new frameworks.

#8795 indicates that the reference to CachedWorld is merely a historical artifact. Therefore, I think the wiki should be updated to change CachedWorld to World.