[IMPROVEMENT] Add documentation Email and Slack notifiers #705

Author: vincent-olivert-riera

docs/conf/django.rst

@@ -9,17 +9,16 @@ All available django settings (not every setting may apply to promgen)
 are listed in the `django
 reference <https://docs.djangoproject.com/en/1.11/ref/settings/>`__.
 
+.. _smtp_config:
 Configuring an SMTP Server
 --------------------------
 
 An SMTP server for sending outgoing mail can be configured this way:
 
 .. code-block:: yaml
 
-    promgen.notification.email:
-      sender: promgen@example.com
-
     django:
+      DEFAULT_FROM_EMAIL: promgen@example.com
       EMAIL_HOST: mail.example.com
       EMAIL_PORT: 587
       EMAIL_HOST_USER: user@example.com

docs/conf/notification.rst

@@ -3,6 +3,20 @@ Configuring Notification Plugins
 
 Different settings for the Notification Plugins can be defined in the ``promgen.yml`` file.
 
+Email
+---------------------
+
+An SMTP server for sending outgoing mail can be configured by adding Django email settings
+(see :ref:`smtp_config`).
+The **email's sender address** either can be set using the ``DEFAULT_FROM_EMAIL`` Django setting
+or by setting the ``sender`` configuration as shown below. If both are set, the ``sender``
+configuration will take precedence.
+
+.. code-block:: yaml
+
+    promgen.notification.email:
+      sender: promgen@example.com
+
 PagerDuty
 ---------------------
 
@@ -18,3 +32,16 @@ PagerDuty API-compatible URLs and alert severity mapping can be configured this
         debug: info
         major: error
         minor: warning
+
+Slack
+---------------------
+
+The proxy configuration specifies the proxy server that Promgen should use when sending
+notifications to Slack. This is useful if your environment requires outgoing requests to go
+through a proxy for security or network policy reasons. If your environment does not require a
+proxy, you can basically ignore this setting or set it to an empty string.
+
+.. code-block:: yaml
+
+    promgen.notification.slack:
+      proxy: http://slack-proxy.example.com:8080