Documentation for including core styles is not clear

As of alpha.7, applications using the components need to include the core styles in addition to individual components.

• All core styles should be consolidated into a single theme file under @angular/material/core.
• Our getting started guide should reflect this step.

Missing these styles can manifest several odd effects, such as:

• Ripples look insane
• Overlays are not positioned correctly.

[tommysella]

Even though it’s described in the https://github.com/angular/material2/blob/master/GETTING_STARTED.md, it would be good to make it more clear that it’s a requirement, and really need to be included.

[alexjoverm]

I must point out @tommysella comment, I’ve spent some precious time finding out why the components were not styling correctly, till I included a theme. It doesn’t looks like required in the docs.