Add note about not-supported white-space-collapse: discard

files/en-us/web/css/white-space-collapse/index.md

@@ -48,7 +48,11 @@ The `white-space-collapse` property is specified as a single keyword chosen from
     - A line-breaking opportunity exists after every preserved white space character, including between white space characters.
     - Preserved spaces take up space and do not hang, thus affecting the box's intrinsic sizes ({{cssxref("min-content")}} size and {{cssxref("max-content")}} size).
 
-> **Note:** _Segment break characters_ are characters such as line feeds that cause text to break onto new lines.
+> [!NOTE]
+> _Segment break characters_ are characters such as line feeds that cause text to break onto new lines.
+
+> [!NOTE]
+> The [CSS text](/en-US/docs/Web/CSS/CSS_text) module defines a `discard` value for the `white-space-collapse` property to discard all white space in the element, however, this is not supported in any browsers.
 
 ## Collapsing of white space