add FerrugemJS library reference in documentation.
add FerrugemJS library reference in documentation.

Add FerrugemJS reference in documentation.
google/incremental-dom,PolymerLabs/incremental-dom,sparhami/incremental-dom,sparhami/incremental-dom,sparhami/incremental-dom,google/incremental-dom,jridgewell/incremental-dom,jridgewell/incremental-dom,google/incremental-dom,PolymerLabs/incremental-dom,PolymerLabs/incremental-dom,sparhami/incremental-dom,jridgewell/incremental-dom