Clarify process for running tests, and fix a spelling error
Clarify process for running tests, and fix a spelling error

Zirro/jsdom,fiftin/jsdom,tmpvar/jsdom,Joris-van-der-Wel/jsdom,Joris-van-der-Wel/jsdom,mbostock/jsdom,mzgol/jsdom,Sebmaster/jsdom,fiftin/jsdom,Sebmaster/jsdom,Zirro/jsdom,mbostock/jsdom,Sebmaster/jsdom,nicolashenry/jsdom,fiftin/jsdom,tmpvar/jsdom,snuggs/jsdom,mzgol/jsdom,mzgol/jsdom,Joris-van-der-Wel/jsdom,nicolashenry/jsdom,snuggs/jsdom,mbostock/jsdom,nicolashenry/jsdom