Updated README to include info on flushing DNS cache.
Updated README to include info on flushing DNS cache.

gfyoung/hosts,ashneo76/hosts,usrjim/hosts,StevenBlack/hosts,netconstructor/hosts,maxmurder/hosts,WillPresley/hosts,FrancoGag/hosts,FrancoGag/hosts,borisschapira/hosts,maxmurder/hosts,sampaisley/hosts,gfyoung/hosts,StevenBlack/hosts,WillPresley/hosts,bmcculley/hosts