Documentation/x86: Introduce enclave runtime management section

mainline inclusion
from mainline-6.0-rc1
commit 629b5155
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5USAM


CVE: NA

Intel-SIG: commit 629b5155 Documentation/x86: Introduce enclave
runtime management section.
Backport for SGX EDMM support.

--------------------------------

Enclave runtime management is introduced following the pattern
of the section describing enclave building. Provide a brief
summary of enclave runtime management, pointing to the functions
implementing the ioctl()s that will contain details within their
kernel-doc.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/1da0b9a938b28e68e6870ebd5291490d680e700b.1652137848.git.reinette.chatre@intel.com


Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>