MAINTAINERS: Cover SGX documentation file with X86/KVM section

Cc: Yang Zhong <yang.zhong@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211007175612.496366-2-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -418,6 +418,7 @@ M: Marcelo Tosatti <mtosatti@redhat.com>
 L: kvm@vger.kernel.org
 S: Supported
 F: docs/amd-memory-encryption.txt
+F: docs/system/i386/sgx.rst
 F: target/i386/kvm/
 F: target/i386/sev*
 F: scripts/kvm/vmxcap