qapi-schema: Introspection doc is in the wrong section, fix

Bug: introspection documentation is in section "Tracing commands".

Cause: sub-schema qapi/introspect.json lacks a section header, and
therefore goes into whatever section precedes its include.

Fix: add a section header.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1503602048-12268-3-git-send-email-armbru@redhat.com>

qapi/introspect.json

 # -*- Mode: Python -*-
 #
-# QAPI/QMP introspection
-#
 # Copyright (C) 2015 Red Hat, Inc.
 #
 # Authors:
@@ -10,6 +8,10 @@
 # This work is licensed under the terms of the GNU GPL, version 2 or later.
 # See the COPYING file in the top-level directory.
 
+##
+# = QMP introspection
+##
+
 ##
 # @query-qmp-schema:
 #