Fix a link in README.md (#881)

[examples/react-babel-karma-gulp-fork-ts-checker](https://github.com/TypeStrong/ts-loader/blob/master/examples/react-babel-karma-gulp-fork-ts-checker) does not exist. 

Replaced with [examples/react-babel-karma-gulp)(https://github.com/TypeStrong/ts-loader/tree/master/examples/react-babel-karma-gulp).

Author: Kinrany

README.md

@@ -26,7 +26,7 @@ As your project becomes bigger, compilation time increases linearly. It's becaus
 
 You probably don't want to give up type checking; that's rather the point of TypeScript. So what you can do is use the [fork-ts-checker-webpack-plugin](https://github.com/Realytics/fork-ts-checker-webpack-plugin). It runs the type checker on a separate process, so your build remains fast thanks to `transpileOnly: true` but you still have the type checking. Also, the plugin has several optimizations to make incremental type checking faster (AST cache, multiple workers).
 
-If you'd like to see a simple setup take a look at [our simple example](examples/fork-ts-checker/). For a more complex setup take a look at our [more involved example](examples/react-babel-karma-gulp-fork-ts-checker).
+If you'd like to see a simple setup take a look at [our simple example](examples/fork-ts-checker/). For a more complex setup take a look at our [more involved example](examples/react-babel-karma-gulp).
 
 If you'd like to make things even faster still (I know, right?) then you might want to consider using ts-loader with [happypack](https://github.com/amireh/happypack) which speeds builds by parallelising work. (This should be used in combination with [fork-ts-checker-webpack-plugin](https://github.com/Realytics/fork-ts-checker-webpack-plugin) for typechecking.) If you'd like to see a simple setup take a look at [our simple example](examples/happypack/). For a more complex setup take a look at our [more involved example](examples/react-babel-karma-gulp-happypack).