Document some features

README.md

@@ -1,3 +1,5 @@
+## Usage
+
 Meta-slint requires:  
 
 ```
@@ -9,4 +11,25 @@ meta-slint
 Check the [layer.conf](conf/layer.conf) LAYERSERIES_COMPAT_meta for yocto version compatibility   
 
 For local version locking just copy the slint-cpp_x.x.x.bb and modify the SLINT_REV 
-and set PREFERRED_VERSION_slint-cpp = "x.x.x"
+and set PREFERRED_VERSION_slint-cpp = "x.x.x"
+
+## Features
+
+For git builds and builds from Slint version 1.3 onwards, certain features are
+configurable via `PACKAGECONFIG`.
+
+| Feature Name       | Description                         | Enabled by Default |
+|--------------------|-------------------------------------|--------------------|
+| `renderer-skia`    | Skia OpenGL renderer                | Yes                |
+| `renderer-femtovg` | Lightweight FemtoVG OpenGL renderer | No                 |
+| `backend-linuxkms` | Backend for rendering via KMS/DRM   | No                 |
+| `interpreter`      | C++ API for Slint Interpreter       | Yes                |
+
+Set the `PACKAGECONFIG:pn-slint-cpp` variable in your `conf/local.conf` to tweak.
+For example, to disable the Skia renderer, enable FemtoVG, and the linuxkms
+backend, set them like this:
+
+```
+PACKAGECONFIG:append:pn-slint-cpp = " backend-linuxkms renderer-femtovg "
+PACKAGECONFIG:remove:pn-slint-cpp = " renderer-skia "
+```