qapi: Cleanup SGX related comments and restore @section-size

qapi: Cleanup SGX related comments and restore @section-size

The SGX NUMA patches were merged into Qemu 7.0 release, we need
clarify detailed version history information and also change
some related comments, which make SGX related comments clearer.

The QMP command schema promises backwards compatibility as standard.
We temporarily restore "@section-size", which can avoid incompatible
API breakage. The "@section-size" will be deprecated in 7.2 version.

Suggested-by: Daniel P. Berrangé <[email protected]>
Signed-off-by: Yang Zhong <[email protected]>
Reviewed-by: Daniel P. Berrangé <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <20220120223104[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>