Consider a section on cache management for ActivityPub spec

[evanp]

The spec mentions caching remote objects in several parts of the document. It may be worthwhile to set out some basic principles of cache management in its own section, so that the discussions of managing the cache in the sections on each type of activity are part of a more cohesive whole.

Note that in the ActivityPub spec this is usually called a "local representation" of the object, and the word "cache" is primarily used for HTTP Caching.