[9.0.0 Release] Release schedule

Hello everyone,

Even though 8.0.1 isn't quite out the door yet, it's time to start
planning for the next major release, 9.0.0.

This is my proposed schedule:

- 18 July 2019: Branch, rc1 soon after
- 7 August: rc2
- 28 August: final (not slipping past first half of September).

Please let me know what you think.

Thanks,
Hans

The schedule is now on the llvm.org web site.

Thanks,
Hans