doc: document lib, fix formating/example

Add lib as an optional directory in a template.

Make config_ini.ini example an actual code block using the file from
the jinja2 template.

Format the TEMPLATE-INFO.txt example as plain text (it was
highlighting words like 'in' and 'with'). Also move the whole example
under the bullet item, it was outside of the list. Reformat the input
text to be less than 80 characters.

Author: rouilj

doc/tracker_templates.txt

@@ -33,22 +33,32 @@ Templates contain:
 - modules ``schema.py`` and ``initial_data.py``
 - directories ``html``, ``detectors`` and ``extensions``
   (with appropriate contents)
+- optional directory ``lib`` which contains modules used by the other
+  tracker components
 - optional ``config_ini.ini`` file. It is structured like a tracker's
   ``config.ini`` but contains only headers (e.g. ``[main]``) and
-  *required* parameters that are different from defaults:
-  e.g. ``template_engine = jinja2`` and ``static_files =
-  static``. These settings override the default values saved to the
-  tracker's ``config.ini``.
+  *required* parameters that are different from defaults. For example::
+  
+    [main]
+    template_engine = jinja2
+
+    static_files = static
+
+  These settings override the default values in the tracker's
+  ``config.ini`` when using roundup-admin to install a template.
 - template "marker" file ``TEMPLATE-INFO.txt``, which contains
   the name of the template, a description of the template
   and its intended audience.
 
-An example TEMPLATE-INFO.txt::
+  An example TEMPLATE-INFO.txt:
+
+  .. code-block:: text
 
- Name: classic
- Description: This is a generic issue tracker that may be used to track bugs,
-              feature requests, project issues or any number of other types
-              of issues. Most users of Roundup will find that this template
-              suits them, with perhaps a few customisations.
- Intended-For: All first-time Roundup users
+     Name: classic
+     Description: This is a generic issue tracker that may be used to
+		  track bugs, feature requests, project issues or any
+		  number of other types of issues. Most users of
+		  Roundup will find that this template suits them,
+		  with perhaps a few customisations.
+     Intended-For: All first-time Roundup users