doc: Clarify Routines and Extension Membership - Mailing list pgsql-hackers

Hi.

Reposting this on its own thread.

    Per discussion on -general the documentation for the
    ALTER ROUTINE ... DEPENDS ON EXTENSION and DROP EXTENSION doesn't
    clearly indicate that these dependent routines are treated in a
    similar manner to the extension's owned objects when it comes to
    using RESTRICT mode drop: namely their presence doesn't force
    the drop command to abort.  Clear that up.

David J.