[css-text-3] Clean up list of forced break UAX14 classes. #3516

Author: fantasai

css-text-3/Overview.bs

@@ -1911,7 +1911,7 @@ Line Breaking Details</h3>
       lines always break at each <a>preserved</a> forced break character:
       thus
       for all values, line-breaking behavior defined for
-      the BK, CR, LF, CM, NL, and SG line breaking classes in [[!UAX14]]
+      the BK and NL line breaking classes in [[!UAX14]]
       must be honored.
     <li>Except where explicitly defined otherwise
       (e.g. for ''line-break: anywhere'' or ''overflow-wrap: anywhere'')