doc update.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@5199 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/widgets/Widget.java

 package hudson.widgets;
 
 import hudson.ExtensionPoint;
+import hudson.model.Hudson;
 
 /**
  * Box to be rendered in the side panel.
@@ -12,6 +13,7 @@ import hudson.ExtensionPoint;
  *
  * @author Kohsuke Kawaguchi
  * @since 1.146
+ * @see Hudson#getWidgets() 
  */
 public abstract class Widget implements ExtensionPoint {
     /**