Update xml/System.Runtime.InteropServices/DllImportResolver.xml

Author: jkotas

xml/System.Runtime.InteropServices/DllImportResolver.xml

@@ -39,7 +39,7 @@
 
 The runtime does not do any lifetime management around the handle returned by a <xref:System.Runtime.InteropServices.DllImportResolver>. It is left to the implementation and consuming code to keep the library loaded for as long as necessary and free it if/when desired. 
 
-For each entry point, the resolver is called the first time PInvoke is used. To improve performance, the implementation of the resolver can cache the `libraryName` to handle mapping, as long as the library isn't unloaded via <xref:System.Runtime.InteropServices.NativeLibrary.Free(System.IntPtr)>.
+The resolver is typically called once for each PInvoke entry point. To improve performance, the implementation of the resolver can cache the `libraryName` to handle mapping, as long as the library isn't unloaded via <xref:System.Runtime.InteropServices.NativeLibrary.Free(System.IntPtr)>.
 
       ]]></format>
     </remarks>