ux: added minor help tip to graphite ds settings

public/app/plugins/datasource/graphite/partials/config.html

@@ -7,7 +7,12 @@
 
 <div class="gf-form-group">
 	<div class="gf-form">
-		<span class="gf-form-label width-8">Version</span>
+		<span class="gf-form-label width-8">
+      Version
+      <info-popover mode="right-normal" position="top center">
+        This option controls what functions are available in the Graphite query editor.
+      </info-popover>
+    </span>
 		<select class="gf-form-input gf-size-auto" ng-model="ctrl.current.jsonData.graphiteVersion" ng-options="f.value as f.name for f in ctrl.graphiteVersions"></select>
 	</div>
 </div>