Add basic module template.

This has the core sections for events/server/client/security.

specification/modules/_template.rst

@@ -0,0 +1,47 @@
+Module Heading
+==============
+
+.. _module:short-name:
+
+A short summary of the module. What features does this module provide? An anchor
+should be specified at the top of the module using the format ``module:name``.
+
+Complicated modules may wish to have architecture diagrams or event flows
+(e.g. VoIP call flows) here. Custom subsections can be included but they should
+be used *sparingly* to reduce the risk of putting client or server behaviour
+information in these custom sections.
+
+Events
+------
+List the new event types introduced by this module, if any. If there are no
+new events, this section can be omitted. Event types should be done as
+subsections. The section is intended to document the "common shared event
+structure" between client and server. Deviations from this shared structure
+should be documented in the relevant behaviour section.
+
+example.event.type
+~~~~~~~~~~~~~~~~~~
+There should be JSON Schema docs for this event. You can insert a template like
+so:
+
+{{example_event_type_event}}
+
+Client behaviour
+----------------
+List any new HTTP endpoints. List the steps the client needs to take to
+correctly process this module. Listing what data structures the client should be
+storing to aid implementation is recommended. 
+
+Server behaviour
+----------------
+Does the server need to handle any of the new events in a special way (e.g.
+typing timeouts, presence). Advice on how to persist events and/or requests are
+recommended to aid implementation.
+
+Security considerations
+-----------------------
+This includes privacy leaks: for example leaking presence info. How do
+misbehaving clients or servers impact this module? This section should always be
+included, if only to say "we've thought about it but there isn't anything to do
+here".
+