bug(github docs): mention @angular/cdk in material installation instructions

[julianobrasil]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

github first page should specify @angular/material depends on @angular/cdk

What is the current behavior?

The intallation instructions on github mentions the @angular/cdk dependency just for the latest builds part.

[jelbourn]

We should really just remove this section from the README and point to the getting started guide.

[julianobrasil]

I think removing the installation part entirely and leaving the Getting Started part is sufficient. I'll just include the latest builds installation in the Getting Started part:

npm install --save angular/material2-builds angular/cdk-builds

[julianobrasil]

@jelbourn, I built a PR with these modifications: #5555 (comment). Take a look to see whether it's good.

[alexbjorlig]

What about @angular/animations, is that not a required package as well?

[julianobrasil]

@dauledk, it was already in Getting Started page on github.