Adding pricing red icons css with example.

[fjtc]

What this PR does / why we need it:

Adding the ability to make the pricing icons red.

Special notes for your reviewer:

This one was achieved by adding a new style to _pricing.css called red. I added an example about how to use it inside the exampleSite's plan-1.md. I'm not sure if it is the preferred way to achieve this effect but I'm pretty sure it is the less disruptive one.

Release note:

- Adding the ability to use red icons inside the pricing features;