adding docset for Leaflet (a JavaScript "slippy map" library)

Code for generating this docset lives at https://github.com/drewda/leaflet-docset
adding icon@2x (for Retina screens)
updating docset tgz to reflect commit https://github.com/drewda/leaflet-docset/commit/91bef5ba9676a0f5b830dff1781302474c0277bc
updating docset to reflect commit https://github.com/drewda/leaflet-docset/commit/68b25cdafa5267e718050d0d569ba7ab8743a544
Merge pull request #27 from drewda/master

adding docset for Leaflet (a JavaScript "slippy map" library)