[css-nav-1] spatial-navigation-action should not be inherited

Author: frivoal

css-nav-1/Overview.bs

@@ -1366,6 +1366,7 @@ Name: spatial-navigation-action
 Value: auto | focus | scroll
 Initial: auto
 Applies to: <a>scroll containers</a>
+Inherited: no
 </pre>
 
 When the user triggers spatial navigation in a given direction, the 'spatial-navigation-action' decides