docs: add note on limitations to testing SFCs with jest

Author: eddyerburgh

docs/en/SUMMARY.md

@@ -42,6 +42,6 @@
     * [Choosing a test runner](guides/choosing-a-test-runner.md)
     * [Using with Jest](guides/using-with-jest.md)
     * [Testing SFCs with Jest](guides/testing-SFCs-with-jest.md)
-    * [Testing SFCs with Mocha and webpack](guides/testing-SFCs-with-mocha-webpack.md)
+    * [Testing SFCs with Mocha](guides/testing-SFCs-with-mocha-webpack.md)
     * [Using with Vuex](guides/using-with-vuex.md)  
   * [common gotchas](common-gotchas.md)

docs/en/guides/testing-SFCs-with-jest.md

@@ -1,9 +1,11 @@
-# Using with Jest
+# Testing single file components with Jest
 
 Jest is a test runner developed by Facebook, aiming to come with everything included to get started. [Learn more about Jest](https://facebook.github.io/jest/)  So let's get started.
 
 To test SFCs, we need to compile the files before running them in node.
 
+*Note: Jest uses a jest-vue transformer. It does not contain all the features of vue-loader, like custom block support and style loading. To use them, read the [testing SFCs with Mocha](test-SFCs-with-mocha.md) guide*
+
 ## Setting up Jest
 
 The first thing to do is install Jest: