- Fix incomplete description of minimum protocol version.
- Add mention of the new ConnectionState.OCSPResponse field.
- Clarify session ticket key rotation description.

Change-Id: I6b62d30a4d0e0f84fd2c0e70e8f66ec14e6a5a90
Reviewed-on: https://go-review.googlesource.com/12197Reviewed-by: Rob Pike <r@golang.org>