Use the irregular id when jumping to `functions`
Use the irregular id when jumping to `functions`

Because the "Functions" section heading already uses `#functions` the
individual method uses an irregular id. I missed this in #2514.

documentcloud/underscore,akre54/underscore,tnga/underscore-es,rlugojr/underscore,jashkenas/underscore,jashkenas/underscore,keepgoingwm/underscore,jdelbello/underscore,keepgoingwm/underscore,jdelbello/underscore,documentcloud/underscore,tnga/underscore-es,rlugojr/underscore,akre54/underscore