Docs: add note for view encapsulation

[aamir1995]

Hello!
It took me about 2 hours to figure out why ng2-fullpage isn't working with my project, Then finally i changed my view encapsulation from native to none and now it is working perfectly.
Please add a note in docs about angular 2 view encapsulation that it has to be set to none before setting ng2-fullpage. :)

[vsfedorenko]

@aamir1995 , you are right. Angular 2 has this issue with styles.

It is already done in demo app.component.ts

I'll mention this problem in readme.md. Thank you!

[vsfedorenko]

I've updated readme file. Thank you!