Release 0.22.0 with composable feature extras

docs/supported-signals.md

@@ -33,7 +33,7 @@ when you can select the affected area yourself.
 
 | Backend | Install | Behavior |
 | --- | --- | --- |
-| `cv2` | Core package | Classical OpenCV inpainting |
+| `cv2` | `remove-ai-watermarks[visible]` | Classical OpenCV inpainting |
 | `migan` | `remove-ai-watermarks[migan]` | MI-GAN through ONNX Runtime |
 | `lama` | `remove-ai-watermarks[lama]` | big-LaMa through ONNX Runtime |
 | `auto` | Depends on installed extras | Selects LaMa, then MI-GAN, then OpenCV |
@@ -69,6 +69,9 @@ Pixel based image commands discover these extensions:
 - HEIC and HEIF;
 - AVIF.
 
+HEIC, HEIF, and AVIF pixel decoding requires the independent `heif` extra in
+addition to the selected pixel feature. Metadata scanning does not.
+
 Metadata inspection and removal additionally have container paths for:
 
 - JPEG XL metadata;