p-heading-icon--medium and p-heading-icon--large

[albertkol]

This is about https://vanillaframework.io/docs/patterns/heading-icon

Currently we offer only p-heading-icon--small which sets the size of the icon to 2rem.

I want the icon to be 4rem and it would be nice if we would have p-heading-icon--medium or p-heading-icon--large to achieve that.

Having p-heading-icon--small implies the existence of at least p-heading-icon--large, it was heartbreaking to find out that there is no such thing. </3

Reference to the PR with the local change: https://github.com/canonical-web-and-design/ubuntu.com/pull/8520