wg: warn once on unrecognized items

wg: warn once on unrecognized items

DaveM suggests we do in fact do this. Others on the same thread weren't
happy about the length of the proposed message, so we also give a bit of
a less dramatic warning.

This reverts commit a2cc976a3b572cf308cc2d97c080eacac60416fe.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>