Allow the room directory to order by relevance rather than population

The spec has a firm requirement that the room directory and any of its results must be ordered by population. Servers (or clients) should be free to organize them however they want.

Start by reviewing the room-directory specification and its requirement that the directory and results be ordered by population. Determine the intended wording and scope for allowing servers or clients to order by relevance instead. Done means the specification clearly permits relevance-based ordering without leaving the ordering rule ambiguous.

Written by the indexing model from the issue text.