Add PR number to changelog

Author: JakeQZ

CHANGELOG.md

@@ -12,7 +12,7 @@ Please also have a look at our
 
 - Partial support for CSS Color Module Level 4:
   - `rgb` and `rgba`, and `hsl` and `hsla` are now aliases (#797}
-  - Parse color functions that use the "modern" syntax
+  - Parse color functions that use the "modern" syntax (#800)
 - Add official support for PHP 8.4 (#657)
 - Support arithmetic operators in CSS function arguments (#607)
 - Add support for inserting an item in a CSS list (#545)