Precise the manual: <restrict> uses AND for combining nested resource selectors

manual/Types/resources.html

@@ -499,8 +499,9 @@ platforms.
   <h4>Parameters specified as nested elements</h4>
   <p>A single resource collection is required.</p>
   <p>Nested resource selectors are used to "narrow down" the included
-    resources. These are patterned after <a href="selectors.html">file
-    selectors</a> but are, unsurprisingly, targeted to resources.
+    resources, combined via a logical <i>AND</i>. These are patterned 
+    after <a href="selectors.html">file selectors</a> but are, 
+    unsurprisingly, targeted to resources.
     Several built-in resource selectors are available in the internal
     <a href="antlib.html">antlib</a>
     <code>org.apache.tools.ant.types.resources.selectors</code>: