docs(getting-started): update HammerJS instructions (#2383)

Author: jelbourn

guides/getting-started.md

@@ -39,39 +39,27 @@ use a pre-built theme, or define your own custom theme.
 
 :trident:  See the [theming guide](guides/theming.md) for instructions.
 
-### Additional setup for `md-slide-toggle` and `md-slider`:
-The slide-toggle and slider components have a dependency on [HammerJS](http://hammerjs.github.io/).
+### Additional setup for gestures
+Some components ()`md-slide-toggle`, `md-slider`, `mdTooltip`) rely on 
+[HammerJS](http://hammerjs.github.io/) for gestures. In order to get the full feature-set of these
+components, HammerJS must be loaded into the application.
 
-Add HammerJS to your application via [npm](https://www.npmjs.com/package/hammerjs), a CDN 
+You can add HammerJS to your application via [npm](https://www.npmjs.com/package/hammerjs), a CDN 
 (such as the [Google CDN](https://developers.google.com/speed/libraries/#hammerjs)), or served 
 directly from your app.
 
 #### If you want to include HammerJS from npm, you can install it:
 
 ```bash
 npm install --save hammerjs 
-npm install --save-dev @types/hammerjs
 ```
 
-Import HammerJS on your app's module.
-
+After installing, import HammerJS on your app's module.
 **src/app/app.module.ts**
 ```ts
 import 'hammerjs';
 ```
 
-Finally, you need to add `hammerjs` to the `types` section of your `tsconfig.json` file:
-
-```json
-{
-  "compilerOptions": {
-    "types": [
-      "hammerjs"
-    ]
-  }
-}
-```
-
 ## Configuring SystemJS
 If your project is using SystemJS for module loading, you will need to add `@angular/material` 
 to the SystemJS configuration: