WebGLRenderer: Deprecate useLegacyLights, change default to false. (#542)

* WebGLRenderer: Deprecate useLegacyLights, change default to false.

* Update WebGLRenderer.js

Author: Methuselah96

types/three/src/renderers/WebGLRenderer.d.ts

@@ -211,6 +211,8 @@ export class WebGLRenderer implements Renderer {
     get coordinateSystem(): typeof WebGLCoordinateSystem;
 
     /**
+     * @deprecated Migrate your lighting according to the following guide:
+     * https://discourse.threejs.org/t/updates-to-lighting-in-three-js-r155/53733.
      * @default true
      */
     useLegacyLights: boolean;