document that colorToAlpha removes the color everywhere

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ljnxm1Qjrocq1izGajLx8J

Author: matmen

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - **`colorToAlpha(color, options)`** (#39): makes a color transparent like GIMP's "Color to Alpha", antialiased edges
   become translucent instead of keeping a fringe of the removed color. Without a color, the top left pixel's is used.
+  The color is removed everywhere in the image, not only from a connected background.
 
 ## 3.0.0
 

src/image.ts

@@ -1179,7 +1179,9 @@ export class Image {
     /**
      * Makes a color transparent, like GIMP's "Color to Alpha": the color is removed from every pixel and replaced by
      * transparency, so pixels that are partly the color (e.g. antialiased edges against a background) become
-     * semi-transparent instead of keeping a fringe of it
+     * semi-transparent instead of keeping a fringe of it.
+     * The color is removed everywhere in the image, not only from a connected background: removing a white
+     * background also makes white areas inside the subject (e.g. eyes in a logo) transparent
      * @param color The color to remove, by default the color of the top left pixel (e.g. a background)
      * @param options See {@link ColorToAlphaOptions}
      */