[landing] added new team members

Summary:
added new team members, had to make one small style change to fix case when team member does not have twitter or github (see image below for reference)

Next diff:

1. Will make small style changes to make the layout a bit cleaner

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Linear Task: ENG-1506

Test Plan:
Please see the screenshot to see the before and after:

Before:

After:

Reviewers: atul, rohan, abosh, ashoat

Reviewed By: atul, rohan, ashoat

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5295