[css-text-3] Make the definition of break-spaces consistent with the details

Closes w3c#4522

Author: frivoal

css-text-3/Overview.bs

@@ -824,8 +824,9 @@ Text Processing</h3>
       except that:
       * Any sequence of <a>preserved</a> [=white space=] always takes up space,
         including at the end of the line.
-      * A line breaking opportunity exists after every <a>preserved</a> <a>white space</a> character,
-        including between [=white space characters=].
+      * A line breaking opportunity exists after every <a>preserved</a> <a>white space</a> character
+        and [=other space separators=],
+        including between them.
 
         <wpt>
           overflow-wrap/overflow-wrap-break-word-002.html