Update build doc to Xcode 8.2.1
Update build doc to Xcode 8.2.1

electron/electron,thomsonreuters/electron,miniak/electron,miniak/electron,joaomoreno/atom-shell,shiftkey/electron,seanchas116/electron,renaesop/electron,renaesop/electron,rajatsingla28/electron,brenca/electron,rreimann/electron,joaomoreno/atom-shell,the-ress/electron,tonyganch/electron,bpasero/electron,gerhardberger/electron,aliib/electron,wan-qy/electron,brenca/electron,electron/electron,joaomoreno/atom-shell,aliib/electron,wan-qy/electron,Floato/electron,electron/electron,rreimann/electron,renaesop/electron,gerhardberger/electron,miniak/electron,thomsonreuters/electron,biblerule/UMCTelnetHub,thompsonemerson/electron,the-ress/electron,brenca/electron,gerhardberger/electron,bpasero/electron,the-ress/electron,twolfson/electron,tonyganch/electron,gerhardberger/electron,rreimann/electron,wan-qy/electron,Floato/electron,biblerule/UMCTelnetHub,shiftkey/electron,aliib/electron,biblerule/UMCTelnetHub,tonyganch/electron,seanchas116/electron,seanchas116/electron,aliib/electron,brenca/electron,aliib/electron,twolfson/electron,shiftkey/electron,Floato/electron,bpasero/electron,tonyganch/electron,bpasero/electron,wan-qy/electron,shiftkey/electron,twolfson/electron,seanchas116/electron,twolfson/electron,thompsonemerson/electron,thomsonreuters/electron,tonyganch/electron,brenca/electron,shiftkey/electron,rajatsingla28/electron,thomsonreuters/electron,electron/electron,the-ress/electron,rreimann/electron,rreimann/electron,electron/electron,biblerule/UMCTelnetHub,twolfson/electron,electron/electron,gerhardberger/electron,miniak/electron,the-ress/electron,miniak/electron,the-ress/electron,shiftkey/electron,thompsonemerson/electron,rajatsingla28/electron,aliib/electron,joaomoreno/atom-shell,seanchas116/electron,Floato/electron,rajatsingla28/electron,twolfson/electron,thomsonreuters/electron,renaesop/electron,bpasero/electron,Floato/electron,bpasero/electron,gerhardberger/electron,electron/electron,thompsonemerson/electron,wan-qy/electron,miniak/electron,biblerule/UMCTelnetHub,joaomoreno/atom-shell,thomsonreuters/electron,renaesop/electron,joaomoreno/atom-shell,renaesop/electron,brenca/electron,biblerule/UMCTelnetHub,tonyganch/electron,rreimann/electron,rajatsingla28/electron,thompsonemerson/electron,Floato/electron,rajatsingla28/electron,wan-qy/electron,the-ress/electron,bpasero/electron,thompsonemerson/electron,seanchas116/electron,gerhardberger/electron