Update L1 Advisors Listing in FE

[BraveNewDeFi]

Overview

The L1 Advisors listing (Product ID: 273) is missing some copy on the Cover Buy page.

• Needs to include a link to the Annex
• Needs to display the protocols included in the listing

You can find the copy we need to add here.

Updates to Make

1. Update the copy on the buy cover page for this listing
2. Fix the typo that appears for the Nexus Mutual Cover T&Cs pictured in the screenshot below
3. Unpin the L1 Advisors listing from the Browse Covers page. We should only have the Entry, Essential and Elite Covers pinned on that page.