add working hyperkitty config

templates/mailman-hyperkitty.py.j2

@@ -0,0 +1,20 @@
+# This is the mailman extension configuration file to enable HyperKitty as an
+# archiver. Remember to add the following lines in the mailman.cfg file:
+#
+# [archiver.hyperkitty]
+# class: mailman_hyperkitty.Archiver
+# enable: yes
+# configuration: /etc/mailman3/mailman-hyperkitty.cfg
+#
+
+[general]
+
+# This is your HyperKitty installation, preferably on the localhost. This
+# address will be used by Mailman to forward incoming emails to HyperKitty
+# for archiving. It does not need to be publicly available, in fact it's
+# better if it is not.
+base_url: http://localhost/mailman3/hyperkitty/
+
+# Shared API key, must be the identical to the value in HyperKitty's
+# settings.
+api_key: {{ mailman.archiver.key }}