Getting Started Guide missing a step to install @types/hammerjs

[shaozi]

Bug, feature request, or proposal:

Documentation

What is the expected behavior?

New project with angular-cli and tried to add material2 by following Getting Started Guide.
After added a material tag, compile failed with bunch of Cannot find name 'HammerManager'. and Cannot find name 'HammerInput'. errors.

The solution is as in issue #977 to install

npm install --save hammerjs @types/hammerjs

What is the use-case or motivation for changing an existing behavior?

Document usability

Which versions of Angular, Material, OS, browsers are affected?

Latest

[jelbourn]

@shaozi we do mention it: https://github.com/angular/material2/blob/master/GETTING_STARTED.md#additional-setup-for-md-slide-toggle-and-md-slider

Do you want to send a PR to make this more specific?

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}