Update README.md

Highlighted the need for render target stencil buffer.

README.md

@@ -1,6 +1,3 @@
-/work in progress.../
-
-
 NanoVG
 ==========
 
@@ -30,7 +27,9 @@ The first parameter defines flags for creating the renderer.
 - `NVG_ANTIALIAS` means that the renderer adjusts the geometry to include anti-aliasing. If you're using MSAA, you can omit this flags. 
 - `NVG_STENCIL_STROKES` means that the render uses better quality rendering for (overlapping) strokes. The quality is mostly visible on wider strokes. If you want speed, you can omit this flag.
 
-Currently there is an OpenGL back-end for NanoVG: [nanovg_gl.h](/src/nanovg_gl.h) for OpenGL 2.0, OpenGL ES 2.0, OpenGL 3.2 core profile and OpenGL ES 3. The implementation can be chosen using a define as in above example. See the header file and examples for further info.
+Currently there is an OpenGL back-end for NanoVG: [nanovg_gl.h](/src/nanovg_gl.h) for OpenGL 2.0, OpenGL ES 2.0, OpenGL 3.2 core profile and OpenGL ES 3. The implementation can be chosen using a define as in above example. See the header file and examples for further info. 
+
+*NOTE:* The render target you're rendering to must have stencil buffer.
 
 ## Drawing shapes with NanoVG
 
@@ -61,7 +60,7 @@ nvgFill(vg);
 ## Rendering is wrong, what to do?
 
 - make sure you have created NanoVG context using one of the `nvgCreatexxx()` calls
-- make sure you have initialised OpenGL with stencil buffer
+- make sure you have initialised OpenGL with *stencil buffer*
 - make sure you have cleared stencil buffer
 - make sure all rendering calls happen between `nvgBeginFrame()` and `nvgEndFrame()`
 - to enable more checks for OpenGL errors, add `NVG_DEBUG` flag to `nvgCreatexxx()`