config: clh: Mention supported TEEs

Let's mention the supported TEEs to be used with confidential guests.

Right now, Cloud Hyperisor supports only Intel TDX, used together with
TD Shim.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

src/runtime/config/configuration-clh.toml.in

@@ -28,6 +28,9 @@ image = "@IMAGEPATH@"
 #   - Memory Hotplug
 #   - NVDIMM devices
 #
+# Supported TEEs:
+# * Intel TDX
+#
 # Default false
 # confidential_guest = true