MAINTAINERS: Add entry for Guest X86 HAXM CPUs

HAXM covers below files:
include/sysemu/hax.h
target/i386/hax-*

V2: Add HAXM github page for wiki and issue tracking.

Cc: Wenchao Wang <wenchao.wang@intel.com>
Cc: Hang Yuan <hang.yuan@intel.com>
Reviewed-by: Hang Yuan <hang.yuan@intel.com>
Signed-off-by: Colin Xu <colin.xu@intel.com>
Message-Id: <20200228012046.6629-1-colin.xu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -436,6 +436,17 @@ F: include/hw/block/dataplane/xen*
 F: include/hw/xen/
 F: include/sysemu/xen-mapcache.h
 
+Guest CPU Cores (HAXM)
+---------------------
+X86 HAXM CPUs
+M: Wenchao Wang <wenchao.wang@intel.com>
+M: Colin Xu <colin.xu@intel.com>
+L: haxm-team@intel.com
+W: https://github.com/intel/haxm/issues
+S: Maintained
+F: include/sysemu/hax.h
+F: target/i386/hax-*
+
 Hosts
 -----
 LINUX