Add new links to pricing duo section

Step 1: What is changing in this MR?

Contentful entry to be published when merging: https://app.contentful.com/spaces/xz1dnu24egyd/environments/master/entries/3uwIEJT93Q7DMkDGYrZgnM?previousEntries=5KkdRv3X2CzGCGdk9dYSsI&focusedField=internalName

Production	Review app
https://about.gitlab.com/pricing/	https://3774-duo-card.about.gitlab-review.app/pricing/
https://about.gitlab.com/gitlab-duo/#pricing	https://3774-duo-card.about.gitlab-review.app/gitlab-duo/#pricing

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

Closes #3774 (closed)