new k5wiki accounts only available by request

[Tom Yu]

I have turned off automatic registration for k5wiki.  If you would
like an account for editing the wiki, and do not already have one,
please ask me or krbcore at mit.edu, including with your desired username
in the request.

Too many spammers were registering for accounts and posting spam.
(They were managing to get past the automatic e-mail verification.)
Turning on CAPTCHA or similar protection would take more effort than
requiring sysops to manually create accounts, and there was some
preference against CAPTCHAs during an informal poll.

Apologies for the inconvenience.