message: Update RELEASE_NOTES for 1.9.12
diff: @@ -5,11 +5,15 @@ A new header is inserted each time a *tag* is created.
  ## Next release (main branch)
  +## v1.9.13
  +
  ## v1.9.12
  -- Fixed GL errors seen with MSAA on WebGL.
  +- engine: Fixed GL errors seen with MSAA on WebGL.
  Warning: this can affect multisampling behavior on devices that do not support OpenGL ES 3.1
  -- Added new `getVertexIndex()` API for vertex shaders.
  +- materials: Added new `getVertexIndex()` API for vertex shaders.
  +- samples: RenderTarget demo now disables post-processing in offscreen view and creates depth attachment.
  +- gltfio: Fix, animation jolt when time delta is very small.
  ## v1.9.11
  