tests/qapi-schema: Fix feature documentation testing

Commit 8aa3a33e44 "tests/qapi-schema: Test for good feature lists in
structs" made test-qapi.py show features, but neglected to show their
documentation.  Fix that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191024110237.30963-5-armbru@redhat.com>
diff --git a/tests/qapi-schema/test-qapi.py b/tests/qapi-schema/test-qapi.py
index 2bd9fd8..bad14ed 100755
--- a/tests/qapi-schema/test-qapi.py
+++ b/tests/qapi-schema/test-qapi.py
@@ -117,6 +117,8 @@
         print('    body=\n%s' % doc.body.text)
         for arg, section in doc.args.items():
             print('    arg=%s\n%s' % (arg, section.text))
+        for feat, section in doc.features.items():
+            print('    feature=%s\n%s' % (feat, section.text))
         for section in doc.sections:
             print('    section=%s\n%s' % (section.name, section.text))