fix(index.d.ts) typo 
fix(index.d.ts) typo 

replaced 'frictionStuffness' by 'frictionStiffness'
mcliment/DefinitelyTyped,nycdotnet/DefinitelyTyped,benishouga/DefinitelyTyped,aciccarello/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,benliddicott/DefinitelyTyped,magny/DefinitelyTyped,alexdresko/DefinitelyTyped,abbasmhd/DefinitelyTyped,GiedriusGrabauskas/DefinitelyTyped,dsebastien/DefinitelyTyped,zuzusik/DefinitelyTyped,zuzusik/DefinitelyTyped,aciccarello/DefinitelyTyped,markogresak/DefinitelyTyped,alexdresko/DefinitelyTyped,benishouga/DefinitelyTyped,arusakov/DefinitelyTyped,isman-usoh/DefinitelyTyped,jimthedev/DefinitelyTyped,chrootsu/DefinitelyTyped,ashwinr/DefinitelyTyped,georgemarshall/DefinitelyTyped,jimthedev/DefinitelyTyped,GiedriusGrabauskas/DefinitelyTyped,AgentME/DefinitelyTyped,QuatroCode/DefinitelyTyped,georgemarshall/DefinitelyTyped,arusakov/DefinitelyTyped,magny/DefinitelyTyped,laurentiustamate94/DefinitelyTyped,rolandzwaga/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,AgentME/DefinitelyTyped,jimthedev/DefinitelyTyped,georgemarshall/DefinitelyTyped,aciccarello/DefinitelyTyped,georgemarshall/DefinitelyTyped,isman-usoh/DefinitelyTyped,borisyankov/DefinitelyTyped,dsebastien/DefinitelyTyped,arusakov/DefinitelyTyped,rolandzwaga/DefinitelyTyped,AgentME/DefinitelyTyped,chrootsu/DefinitelyTyped,minodisk/DefinitelyTyped,zuzusik/DefinitelyTyped,minodisk/DefinitelyTyped,abbasmhd/DefinitelyTyped,borisyankov/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,ashwinr/DefinitelyTyped,QuatroCode/DefinitelyTyped,amir-arad/DefinitelyTyped,AgentME/DefinitelyTyped,benishouga/DefinitelyTyped,one-pieces/DefinitelyTyped,nycdotnet/DefinitelyTyped