Update AppleDoc install instructions
Update AppleDoc install instructions

@tomaz tagged a new version of AppleDoc which resolves the issue requiring
the `--HEAD` param to `brew`, and @adamv [pulled in the change](https://github.com/mxcl/homebrew/pull/14693)
to mxcl/homebrew that both updates to the new code and also uses
the [new compile-time template location](https://github.com/tomaz/appledoc/pull/231)
to avoid the second step.
ashfurrow/CocoaPods,vivekshukla-mob-ibtech/Repository,Ashton-W/CocoaPods,0xced/CocoaPods,orta/CocoaPods,mglidden/CocoaPods,mglidden/CocoaPods,mglidden/CocoaPods,segiddins/CocoaPods