update docs to reflect that fillGraph is now per-series.
update docs to reflect that fillGraph is now per-series.

pshevtsov/dygraphs,klausw/dygraphs,panuhorsmalahti/dygraphs,jmptrader/dygraphs,mariolll/dygraphs,mariolll/dygraphs,danvk/dygraphs,davidmsibley/dygraphs,witsa/dygraphs,pshevtsov/dygraphs,grantadesign/dygraphs,petechap/dygraphs,Akiyah/dygraphs,panuhorsmalahti/dygraphs,klausw/dygraphs,mantyr/dygraphs,reinert/dygraphs,pshevtsov/dygraphs,reinert/dygraphs,mantyr/dygraphs,panuhorsmalahti/dygraphs,mantyr/dygraphs,davidmsibley/dygraphs,Yong-Lee/dygraphs,pshevtsov/dygraphs,jmptrader/dygraphs,vhotspur/dygraphs,Yong-Lee/dygraphs,kbaggott/dygraphs,timeu/dygraphs,cavorite/dygraphs,socib/dygraphs,panuhorsmalahti/dygraphs,cavorite/dygraphs,mcanthony/dygraphs,danvk/dygraphs,grantadesign/dygraphs,pshevtsov/dygraphs,petechap/dygraphs,klausw/dygraphs,vhotspur/dygraphs,Yong-Lee/dygraphs,socib/dygraphs,timeu/dygraphs,kbaggott/dygraphs,mcanthony/dygraphs,danvk/dygraphs,cavorite/dygraphs,petechap/dygraphs,witsa/dygraphs,davidmsibley/dygraphs,grantadesign/dygraphs,petechap/dygraphs,danvk/dygraphs,mcanthony/dygraphs,reinert/dygraphs,timeu/dygraphs,witsa/dygraphs,mariolll/dygraphs,reinert/dygraphs,mariolll/dygraphs,klausw/dygraphs,mantyr/dygraphs,Akiyah/dygraphs,jmptrader/dygraphs,Akiyah/dygraphs,grantadesign/dygraphs,davidmsibley/dygraphs,panuhorsmalahti/dygraphs,klausw/dygraphs,petechap/dygraphs,mantyr/dygraphs,reinert/dygraphs,kbaggott/dygraphs,timeu/dygraphs,danvk/dygraphs,mcanthony/dygraphs,witsa/dygraphs,jmptrader/dygraphs,socib/dygraphs,jmptrader/dygraphs,socib/dygraphs,witsa/dygraphs,kbaggott/dygraphs,cavorite/dygraphs,timeu/dygraphs,mcanthony/dygraphs,grantadesign/dygraphs,kbaggott/dygraphs,vhotspur/dygraphs,Akiyah/dygraphs,Akiyah/dygraphs,mariolll/dygraphs,Yong-Lee/dygraphs,davidmsibley/dygraphs,vhotspur/dygraphs,vhotspur/dygraphs,Yong-Lee/dygraphs