Add hint to expand search terms if implicitly filtered

Add hint to expand search terms if implicitly filtered

I keep accidentally missing some search results when testing because
I'm searching for a tag that only exists on a solved puzzle so something
like:

	/hunt cryptic

is not finding the solved puzzle with the CRYTPIC tag due to the
implicit filtering to only unsolved puzzles.

I still want that implicit filtering, but maybe this nudge will be
helpful in cases like this.