[css-ui-3] Remove redundant text

Part of #13019

Author: frivoal

css-ui-3/Overview.bs

@@ -976,10 +976,6 @@ Values have the following meanings:
 	</pre>
 
 The user agent retrieves the cursor from the resource designated by the URL.
-If the user agent cannot handle the first cursor of a list of cursors,
-it must attempt to handle the second, etc.
-If the user agent cannot handle any user-defined cursor,
-it must use the cursor keyword at the end of the list.
 Conforming user agents may, instead of <<url>>, support <<image>> which is a superset.
 
 The UA must support the following image file formats: