mailman: add template for held messages on users list

Add a note to the held message template which explains that messages
held for being over the list size limit (default: 60K) will not be
approved.  Offer some suggestions to help senders reduce the size of
their messages.

This will save the list moderators the effort of doing this manually and
will prevent senders from waiting for a reply from those moderators.

References
==========
https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org/thread/QIMCJNTLBEDJZEDLAQH53TBTP36VPG54/
https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org/message/ZDVJHWAD64J3VKO5OQ2XITOOQMVL73GC/

Signed-off-by: Todd Zullinger <tmz@pobox.com>

roles/mailman/files/mailman-template-users-list-user-notice-hold.txt

@@ -0,0 +1,25 @@
+Your mail to '$listname' with the subject
+
+    $subject
+
+Is being held until the list moderator can review it for approval.
+
+The message is being held because:
+
+$reasons
+
+Either the message will get posted to the list, or you will receive
+notification of the moderator's decision.
+
+NOTE: If your message has been held due to size, please consider
+this a rejection and a friendly request to reduce the size and
+resend.  The list moderators will not approve such messages.
+
+If you are attaching logs or command output, please trim it to a
+minimal amount (we can ask for more context, if needed).
+
+If you are attaching an image, please crop it to reduce their size.
+
+Also keep in mind that attachments will be encoded by your mail
+client (usually via base64) and this encoding increases the size by
+as much as 33%.

roles/mailman/tasks/main.yml

@@ -235,6 +235,20 @@
   - config
   - mailman
 
+- name: Create lists/users.lists.fedoraproject.org/en template dir
+  file: state=directory path=/var/lib/mailman3/templates/lists/users.lists.fedoraproject.org/en
+  tags:
+  - config
+  - mailman
+
+- name: set list:user:notice:hold template for users list
+  copy: src=mailman-template-users-list-user-notice-hold.txt
+        dest=/var/lib/mailman3/templates/lists/users.lists.fedoraproject.org/en/list:user:notice:hold.txt
+        owner=mailman group=mailman mode=0644
+  tags:
+  - config
+  - mailman
+
 #
 # Crontab
 #