added help screen.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@3860 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/resources/hudson/matrix/MatrixProject/configure-entries.jelly

@@ -30,7 +30,7 @@
     <j:if test="${!empty(app.slaves)}">
       <j:set var="labels" value="${it.labels}" />
       <f:optionalBlock name="multipleNodes" title="Build on multiple nodes" checked="${!empty(labels)}"
-          help="/help/matrix/slave.html">
+          help="/help/matrix/label.html">
         <f:entry title="Node">
           <div id="nodeTree" class="yahooTree" style="border: 1px solid grey; height: 10em; overflow:auto;"></div>
           <script src="${rootURL}/scripts/yui/treeview-${yuiSuffix}.js"></script>

war/resources/help/matrix/label.html

+<div>
+  Specify nodes where builds are performed.
+
+  <ul>
+    <li>
+      If none is selected, Hudson will choose
+      available node to perform a build (this is the same behavior to the free-style
+      project when "tie this project to node" is not selected.) This is useful
+      when the project doesn't have a dependency to any particular node, as
+      it allows Hudson to utilize nodes in optimal fashion.
+    <li>
+      If one is selected, Hudson will always run the build on the specified node
+      (if you select one from "specific nodes")
+      or one of the nodes that belong to the label (if you select one from "label".)
+      This is useful when the build is required to run on a specific computer,
+      or a subset of computers. For example, maybe your build requiers MacOS X.
+    <li>
+      If multiple values are selected, the build matrix will be expanded to include
+      them all, and builds will be performed on all the selected nodes/labels.
+      This is useful for example when you'd like to run tests on Windows, Linux,
+      and Solaris.
+  </ul>
+</div>
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