Update readme

Author: odan

README.md

@@ -12,11 +12,16 @@ Image type detection library for PHP.
 
 ## Features
 
-* Detect image type from file content (not the extension)
-* Supported formats: JPG, GIF, PNG, WEBP, BMP, PSD, TIFF, SVG, ICO, CUR, SWF, AI, HEIC and RAW files
+* Detection the image type by its content (header)
 * No dependencies
 * Very fast
 
+### Supported formats
+
+* JPG, GIF, PNG, WEBP, SVG, BMP, PSD, TIFF, ICO, CUR, SWF, AI
+* HEIC (Apple iPhone photos)
+* RAW: DC3
+
 ## Requirements
 
 * PHP 7.2+