Documentation: make paid plan badges clickable

New doc or update?

• New documentation
• Update existing documentation

Checklists

Documentation blurb

• Doc title

N/A

• Feature overview/description

If I go to any documentation page, for a feature available only on a paid plan, I can see a helpful badge or hint to the right of each header that mentions that plan. Here's an example, next to the "Multi-project pipelines" header at https://docs.gitlab.com/ee/ci/multi_project_pipelines.html

I would suggest making it a link to https://about.gitlab.com/pricing, in addition to the existing tooltip? That would have the benefit of making the pricing page more discoverable.

• Feature use cases

Adopter considering using the feature and needing to quickly assess which plan to choose.