added gulp api docs ref
added gulp api docs ref

Gabriel0402/learn-typescript,ziaukhan/learn-typescript,Hadisaeed/learn-typescript,ziaukhan/learn-typescript,garywu125/learn-typescript,Hadisaeed/learn-typescript,Gabriel0402/learn-typescript,AbdulBasitBashir/learn-typescript,garywu125/learn-typescript,ziaukhan/learn-typescript,panacloud/learn-typescript,zeeshanayaz/learn-typescript,panacloud/learn-typescript,zeeshanayaz/learn-typescript,panacloud/learn-typescript,AbdulBasitBashir/learn-typescript