Setup release notes build using towncrier tool

doc/newsfragments/README.md

@@ -1,12 +1,13 @@
-This is the directory for news snippets used by towncrier: https://github.com/twisted/towncrier
+This is the directory for release note fragments processed by
+[towncrier](https://github.com/hawkowl/towncrier).
 
-When changing code in a way that's visible to an end user please make a new file in this directory.
-It will be removed and integrated into release notes document upon a release of a new version of
-Barrier.
+When making a user-visible change create a file in this directory and it will be automatically be
+included into the release note document when the next release is published.
 
-towncrier has a few standard types of news fragments, signified by the file extension. These are:
+The file extension specifies the type of a change. The following are currently supported:
 
-.feature: Signifying a new feature.
-.bugfix: Signifying a bug fix.
-.doc: Signifying a documentation improvement.
-.removal: Signifying a deprecation or removal of public API.
+ - .feature: a new feature.
+ - .bugfix: a bug fix.
+ - .security: a fix for security issue.
+ - .doc: a documentation improvement.
+ - .removal: a deprecation or removal of functionality.

doc/release_notes/index.md

@@ -0,0 +1,4 @@
+Release notes
+=============
+
+[comment]: <> (towncrier release notes start)

doc/release_notes/index.template.jinja

@@ -0,0 +1,37 @@
+{% for section, _ in sections|dictsort(by='key') %}
+{% set underline = "-" %}
+{% if section %}
+{{section}}
+{{ underline * section|length }}{% set underline = "-" %}
+
+{% endif %}
+{% if sections[section] %}
+{% for category, val in definitions|dictsort if category in sections[section]%}
+
+{{ definitions[category]['name'] }}
+{{ underline * definitions[category]['name']|length }}
+
+{% if definitions[category]['showcontent'] %}
+{% for text, values in sections[section][category]|dictsort(by='value') %}
+- {{ text }}
+{% endfor %}
+{% else %}
+- {{ sections[section][category]['']|sort|join(', ') }}
+
+
+{% endif %}
+{% if sections[section][category]|length == 0 %}
+
+No significant changes.
+
+
+{% else %}
+{% endif %}
+{% endfor %}
+{% else %}
+
+No significant changes.
+
+
+{% endif %}
+{% endfor %}