The new virtual category docs was recently added.
Interestingly enough, FreshPorts has a /docs/ directory, which directly conflics with this. As such, if you were to browe to http://www.freshports.org/docs/, you’d see this:
Index of /docs
Name […]

This is news to me (thanks Pav):
$ make -V VALID_CATEGORIES
accessibility afterstep arabic archivers astro audio benchmarks biology cad chinese comms converters databases deskutils devel docs dns editors elisp emulators finance french ftp games geography german gnome gnustep graphics hamradio haskell hebrew hungarian ipv6 irc japanese java kde kld korean lang linux […]

Welcome to unemployment.
What was ironic about today: At lunch, I dropped off a cheque to the car dealer for the car I’d picked up two Fridays ago. At 2pm, I was fired. DOH!
Bummer.
My resume.
Thank you.