How about the BBEdit manual :-) ?
Anyway, for me it's under the Text Menu: Un/Comment...
I assigned a keyboard command to it, and it might not have one
to begin with (which is probably why it wouldn't show up at the
site you searched...).
Select the text you want to un/comment and use this command.
Note that how it comments depends on what language BBEdit thinks
you intend to be working in -- which you can set by file or by
file type; see Preferences -> Languages.
HTH
Best Regards,
- Bruce
_bruce__van_allen__santa_cruz_ca_