Add /powerdown and /powerup to /help

[I-0]

yeah, for whatever reason, /powerdown and /powerup aren't listed in /help, and i don't think any other like, non-gag commands are missing from /help?

also while we're at it can we get /pd and /pu added as synonyms for them i'm just really lazy

[Nadrew]

Done.

Also added /pu, /powup, /pd, and /powdown