fix(): spelling fix in templating editor

public/app/features/templating/editorCtrl.js

@@ -23,7 +23,7 @@ function (angular, _) {
     $scope.variableTypes = [
       {value: "query",      text: "Query"},
       {value: "interval",   text: "Interval"},
-      {value: "datasource", text: "Datasource"},
+      {value: "datasource", text: "Data source"},
       {value: "custom",     text: "Custom"},
     ];
 

public/app/features/templating/partials/editor.html

@@ -190,7 +190,7 @@
       </div>
 
       <div ng-show="current.type === 'datasource'" class="gf-form-group">
-        <h5 class="section-heading">Datasource Options</h5>
+        <h5 class="section-heading">Data source options</h5>
 
         <div class="gf-form">
           <label class="gf-form-label width-12">Type</label>