Update docs to reflect change to default setting of 'alpha' from true to false made in 0ade4a1d3a2caa4987fb56af1040a7b034c15749.

docs/api/renderers/WebGLRenderer.html

@@ -23,7 +23,7 @@
 		<div>
 		canvas — A [page:Canvas] where the renderer draws its output.<br />
 		precision — shader precision. Can be *"highp"*, *"mediump"* or *"lowp"*.<br />
-		alpha — [page:Boolean], default is *true*.<br />
+		alpha — [page:Boolean], default is *false*.<br />
 		premultipliedAlpha — [page:Boolean], default is *true*.<br />
 		antialias — [page:Boolean], default is *false*.<br />
 		stencil — [page:Boolean], default is *true*.<br />