[landing] address slack comparison touch ups

Summary:
resolves the following slack comparison copy touch up:

https://linear.app/comm/issue/ENG-4627/slack-comparison

Depends on D8792

Test Plan:
Please screenshot:

Reviewers: atul, kamil, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8793