Update ReScript users section

[gkz]

messenger.com no longer uses ReScript. I believe OurUsers.res should be updated to remove both Messenger and Facebook entries.

[chenglou]

Hi George.

Thanks. I reached out to some old teammates and it indeed seems like ReScript is being pushed out. We'll update the site accordingly. Tech choices can be influenced by various factors, though we respect the decision made. Best of luck with Flow.