Pricing Page: Highlight featured plans

[nienn]

From discussion at #4 (comment).

This is just something we briefly talked about in the referenced PR but didn't settle on a decision.

The idea with this issue is:

• to find a way to highlight a plan in both community and corporate pricing cards.
• to decide if we even want to highlight plans in both or either.
• to decide what plan to highlight in community (in corporate the Advanced plan seems to be the obvious choice).