create alias background_lighting -> backlighting
So that users won't try to search for background and then tag background_lightning instead when they look for the tag... before recent edits there are some images under background lightning that aren't really lightning but just lighting...
(backlighting mean background lighting right?)
EDIT: This tag alias has been rejected because it was not approved within 60 days.
EDIT: The tag alias background_lighting -> backlighting (forum #141354) has been rejected by @DanbooruBot.
Updated by a moderator