Summary:
We are asked to include TOS, Privacy Policy and copyright in the website. Added it.
Also changed the github and twitter link to RocksDB's rather than Facebook Open Source's and link to Meta open source's home page.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10491

Test Plan: Test the website locally.

Reviewed By: jay-zhuang

Differential Revision: D38475212

fbshipit-source-id: f73622f8f3d361b4586221ffb6deac4f4a11bb15