Add new metatags to searching cheat sheet

Since the searching cheat sheet isn't a wiki page, I can't just add them myself.

So whoever has the power, please add the arttags:n chartags:n copytags:n metatags to the list. And if there are any other new ones too.

I just spent a while trying to find out what they were...

Huh? They're already listed. Ctrl + F arttags.

There is one undocumented metatag: order:change. It orders posts from least recently edited to most recently edited. order:change_desc sorts in the opposite direction.

Damn, guess I need to get my eyes check out. Thanks for pointing it out.