Also document that it will be changed in a later branch.

These were sort of described in config_assign() documentation, but
not so well.

Closes 31612.

teor authored 5 years ago and Nick Mathewson committed 5 years ago

Closes 31461.

teor authored 5 years ago and Nick Mathewson committed 5 years ago

Part of 31461.

Previously we often referred to "C files" and "H files", which is
more ambiguous than ".c files" and ".h files".

Part of 31314.

Part of 31314.