Please update documentation Hippo CMS External Document Picker

I had some issues implementing the External Document Picker in the ck-editor.

It was not clear that the custom rest api and json should at least contains a icon property, else the results (json) does not come through in the search result box of the popup.
This information should be below the section: 'Implementing your own REST Service for External Document Searches' This would have saved me a hour of two.

http://exdocpickerbase.forge.onehippo.org/richtext-ckeditor/dev-howto.html