message: Update RELEASE_NOTES for 1.9.4
diff: This file contains one line summaries of commits that are worthy of mentioning in release notes.
  A new header is inserted each time a *tag* is created.
  -## Next release (v1.9.5)
  +## Next release (main branch)
  +
  +## v1.9.5
  - Added a new Live Wallpaper Android sample
  - `UiHelper` now supports managing a `SurfaceHolder`.
  @@ -11,7 +13,12 @@ A new header is inserted each time a *tag* is created.
  ## v1.9.4
  -- New `ShadowOptions` control to render Variance Shadow Maps (VSM) with MSAA (experimental).
  +- Add screen space cone tracing (SSCT)
  +- Improvements to VSM shadow quality
  +- New `ShadowOptions` control to render Variance Shadow Maps (VSM) with MSAA (experimental)
  +- Improvements and fixes to screen-space ambient occlusion
  +- gltf_viewer: add --headless option
  +- gltf_viewer: Add new automation UI and functionality
  ## v1.9.3
  