Fix malformed xml

Author: mattbrailsford

NuGet.config

@@ -14,11 +14,10 @@
     <packageSource key="Umbraco Prereleases">
       <package pattern="Umbraco.*" />
     </packageSource>
-  <packageSource key="Umbraco Nightly">
+    <packageSource key="Umbraco Nightly">
       <package pattern="Umbraco.*" />
     </packageSource>
-  </packageSourceMapping>
-  <packageSource key="Umbraco Commerce Unstable">
+    <packageSource key="Umbraco Commerce Unstable">
       <package pattern="Umbraco.Commerce.*" />
     </packageSource>
   </packageSourceMapping>