Update brew installation instructions.
Update brew installation instructions.

Summary: Update brew instructions for installing JDK 8.

Test Plan: CI

Reviewed By: philipjameson, styurin

fbshipit-source-id: 0324d05

rmaz/buck,SeleniumHQ/buck,rmaz/buck,rmaz/buck,brettwooldridge/buck,brettwooldridge/buck,shs96c/buck,SeleniumHQ/buck,kageiit/buck,LegNeato/buck,shs96c/buck,rmaz/buck,SeleniumHQ/buck,Addepar/buck,JoelMarcey/buck,zpao/buck,shs96c/buck,JoelMarcey/buck,JoelMarcey/buck,SeleniumHQ/buck,LegNeato/buck,brettwooldridge/buck,clonetwin26/buck,romanoid/buck,JoelMarcey/buck,romanoid/buck,LegNeato/buck,SeleniumHQ/buck,SeleniumHQ/buck,LegNeato/buck,brettwooldridge/buck,facebook/buck,facebook/buck,zpao/buck,ilya-klyuchnikov/buck,SeleniumHQ/buck,clonetwin26/buck,Addepar/buck,nguyentruongtho/buck,SeleniumHQ/buck,brettwooldridge/buck,shs96c/buck,romanoid/buck,rmaz/buck,romanoid/buck,facebook/buck,Addepar/buck,JoelMarcey/buck,nguyentruongtho/buck,shs96c/buck,shs96c/buck,romanoid/buck,romanoid/buck,LegNeato/buck,clonetwin26/buck,brettwooldridge/buck,rmaz/buck,shs96c/buck,LegNeato/buck,Addepar/buck,shs96c/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,JoelMarcey/buck,brettwooldridge/buck,zpao/buck,kageiit/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,zpao/buck,zpao/buck,LegNeato/buck,rmaz/buck,LegNeato/buck,SeleniumHQ/buck,clonetwin26/buck,ilya-klyuchnikov/buck,clonetwin26/buck,clonetwin26/buck,brettwooldridge/buck,romanoid/buck,Addepar/buck,facebook/buck,JoelMarcey/buck,Addepar/buck,clonetwin26/buck,clonetwin26/buck,Addepar/buck,shs96c/buck,romanoid/buck,romanoid/buck,SeleniumHQ/buck,nguyentruongtho/buck,nguyentruongtho/buck,kageiit/buck,facebook/buck,Addepar/buck,facebook/buck,facebook/buck,brettwooldridge/buck,SeleniumHQ/buck,Addepar/buck,zpao/buck,JoelMarcey/buck,rmaz/buck,nguyentruongtho/buck,clonetwin26/buck,ilya-klyuchnikov/buck,ilya-klyuchnikov/buck,clonetwin26/buck,kageiit/buck,shs96c/buck,rmaz/buck,SeleniumHQ/buck,shs96c/buck,ilya-klyuchnikov/buck,ilya-klyuchnikov/buck,rmaz/buck,SeleniumHQ/buck,Addepar/buck,LegNeato/buck,nguyentruongtho/buck,kageiit/buck,LegNeato/buck,JoelMarcey/buck,romanoid/buck,JoelMarcey/buck,kageiit/buck,romanoid/buck,ilya-klyuchnikov/buck,Addepar/buck,clonetwin26/buck,clonetwin26/buck,romanoid/buck,zpao/buck,LegNeato/buck,rmaz/buck,shs96c/buck,rmaz/buck,brettwooldridge/buck,romanoid/buck,kageiit/buck,Addepar/buck,Addepar/buck,nguyentruongtho/buck,ilya-klyuchnikov/buck,LegNeato/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,rmaz/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,shs96c/buck,clonetwin26/buck,JoelMarcey/buck,LegNeato/buck,ilya-klyuchnikov/buck,JoelMarcey/buck