update repo url in contributing.md
update repo url in contributing.md

thomsonreuters/electron,electron/electron,electron/electron,bpasero/electron,shiftkey/electron,bpasero/electron,shiftkey/electron,thomsonreuters/electron,Floato/electron,seanchas116/electron,Floato/electron,electron/electron,the-ress/electron,shiftkey/electron,bpasero/electron,seanchas116/electron,seanchas116/electron,seanchas116/electron,gerhardberger/electron,electron/electron,the-ress/electron,Floato/electron,Floato/electron,bpasero/electron,gerhardberger/electron,the-ress/electron,thomsonreuters/electron,shiftkey/electron,bpasero/electron,the-ress/electron,seanchas116/electron,gerhardberger/electron,shiftkey/electron,Floato/electron,thomsonreuters/electron,electron/electron,bpasero/electron,gerhardberger/electron,seanchas116/electron,bpasero/electron,thomsonreuters/electron,shiftkey/electron,Floato/electron,gerhardberger/electron,electron/electron,thomsonreuters/electron,electron/electron,gerhardberger/electron,gerhardberger/electron,the-ress/electron,the-ress/electron,the-ress/electron