update docs about template loader

Author: yyx990803

docs/configurations/pre-processors.md

@@ -34,10 +34,10 @@ npm install coffee-loader --save-dev
 
 ### Templates
 
-Processing templates is a little different, because most Webpack template loaders such as `jade-loader` returns a template function instead of compiled HTML string. So instead of using `jade-loader`, we will use `template-html-loader` plus the raw `jade` compiler:
+Processing templates is a little different, because most Webpack template loaders such as `jade-loader` returns a template function instead of compiled HTML string. Instead of using `jade-loader`, we can just install the original `jade`:
 
 ``` bash
-npm install template-html-loader jade --save-dev
+npm install jade --save-dev
 ```
 
 ``` html
@@ -47,6 +47,8 @@ div
 </template>
 ```
 
+> **Important:** If you are using `vue-loader@<8.2.0`, you also need to install `template-html-loader`.
+
 ### Inline Loader Requests
 
 You can use [Webpack loader requests](https://webpack.github.io/docs/loaders.html#introduction) in the `lang` attribute: