Docs update.

Author: photonstorm

README.md

@@ -340,6 +340,7 @@ Please note that Phaser uses a custom build of Pixi and always has done. The fol
 * Graphics.arc has a new argument `segments` that allows you to control how many segments are created when the arc is drawn. The default is 40. Use a higher number for more fidelity, i.e. if you find that reversed arcs are not joining up fully (#2064)
 * PIXI.WebGLMaskManager.pushMask and popMask are now more robust in checking that they have been given valid mask data (#2152)
 * PIXI.WebGLGraphics.stencilBufferLimit is a new integer that allows you to define how many points exist in a Graphics object before Pixi swaps to using the Stencil Buffer to render it. The default is 6 but can be increased. This fixes issues with things like Quadratic curves not rendering as masks in WebGL.
+* If a Display Object with a mask contained a child with a Filter, then the child would not render. The WebGLFilterManager now retains state and creates a new stencil buffer as required (thanks @hightopo #1842)
 
 For changes in previous releases please see the extensive [Version History](https://github.com/photonstorm/phaser/blob/master/CHANGELOG.md).