Add link to makeicns in docs.

[makeicns](https://bitbucket.org/mkae/makeicns) is a little-known command-line program that allows you to create ICNS files from other image formats (JPG, PNG, etc.). Since it is a command-line application it is easily scriptable for automated deployments. I use it to create icons for my app bundle and thought that others might want to know about it.

I wasn't sure if I should commit the rebuilt docs. I looked at other commits that modified the manual and they did not rebuild them, so I followed suit. Please let me know if this is incorrect.