Add missing methods to _.iteratee docs
Add missing methods to _.iteratee docs

The following methods are transformed through `cb()` but are not listed in the
`_.itereatee` documentation:

* findIndex
* findKey
* findLastIndex
* mapObject

I've added them here, and alphabetized the list.

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