Update README about forking RocksDB or submit patches upstream?

[ottok]

Hi!

What is the long-term plan for the TiDB fork of RocksDB 8.10? Have you submitted the patches upstream and plan to use vanilla upstream RocksDB some day in the future? Or do you plan to maintain a permanent fork for RocksDB?

Could the state/plans of the fork be updated into the README file? Currently it is 1:1 the same README as in the upstream RocksDB project.

[Connor1996]

As we have done a lot of changes, I can't see we can use vanilla upstream RocksDB in near future.

[ottok]

Have you tried submitting any of the patches upstream?

[Connor1996]

Yes, some changes are already merged in upstream