[landing] added learn more about comm link to footer

Summary:
Won't land this until the Team Listing part of comm.page has been updated

added learn more about comm link to footer.

Test Plan:
Please view the before and after demo to see the changes I made:

Before:

After:

With margin instead of space:

Reviewers: atul, rohan, abosh

Reviewed By: atul, rohan

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5348