Add FedRAMP section to Pubsec page

Step 1: What is changing in this MR?

Adds FedRAMP section to pubsec page.

• Contentful entry to be published: https://app.contentful.com/spaces/xz1dnu24egyd/environments/master/entries/qnk31KMxbscWx2ALq6vwi?previousEntries=51DJ4HkNueANSrcfSMUEI8&focusedField=internalName

Production	Review app
https://about.gitlab.com/solutions/public-sector/	https://ld-de-fedramp-pubsec.about.gitlab-review.app/solutions/public-sector/

updated #3772 (closed)

Step 2: Ensure that your changes comply with the following, where applicable:

• I, the Assignee, have run Axe tools on any updated pages, and fixed the relevant accessibility issues.
• These changes work on both Safari, Chrome, and Firefox.
• These changes have been reviewed for Visual Quality Assurance and Functional Quality Assurance on Mobile, Desktop, and Tablet.
• These changes work with our Google Analytics and SEO tools.
• These changes have been documented as expected.

Build Variables:

• Use Contentful Preview API