Fixed a missing import in the sample readme.
Fixed a missing import in the sample readme.

For #2.

mindaugasrukas/mock,mbinge/gomock,masagroup/gomock,masagroup/gomock,jmhodges/mock,barum/gomock,epipho/mock,fische/mock,golang/mock,CrowdStrike/gomock,mindaugasrukas/mock,iyee/gomock,jmhodges/mock,iyee/gomock,golang/mock,rafrombrc/gomock,CrowdStrike/gomock,ahjdzx/gomock,qur/gomock,shutej/gomock,barum/gomock,petergtz/pegomock,mbinge/gomock,shutej/gomock,fische/mock,qur/gomock,ahjdzx/gomock,rafrombrc/gomock,petergtz/pegomock,epipho/mock