Docs: Add templates syntax explanation and usage

Author: pszpetkowski

docs/source/index.rst

@@ -11,6 +11,8 @@ Welcome to django-templated-mail documentation!
 
    getting_started
    settings
+   templates_syntax
+   sample_usage
 
 Indices and tables
 ==================

docs/source/sample_usage.rst

@@ -0,0 +1,45 @@
+Sample usage
+============
+
+At first let's discuss the simplest possible use case, where you just wish to
+send an email to a given address and using the given template.
+
+.. code-block:: python
+
+    from templated_mail.mail import BaseEmailMessage
+
+    BaseEmailMessage(template_name='email.html').send(to=['foo@bar.tld'])
+
+This one-liner will do all of the work required to render proper template blocks
+and assign the results to proper email pieces. It will also determine appropriate
+content type (including support for MIME) and send the output message to provided
+list of email address'.
+
+You might also wish to define your own subclass of
+``templated_mail.mail.BaseEmailMessage`` to customize a thing or two.
+What might be most interesting for you is the ``get_context_data`` method,
+which returns context used during template rendering.
+
+.. code-block:: python
+
+    class MyEmailMessage(BaseEmailMessage):
+        def get_context_data(self):
+            context = super(MyEmailMessage, self).get_context_data()
+            context['foo'] = 'bar'
+            return context
+
+You might also provide custom context data using the ``context`` parameter.
+
+.. code-block:: python
+
+    from templated_mail.mail import BaseEmailMessage
+
+    BaseEmailMessage(context={'foo': 'bar'}, template_name='email.html').send(to=['foo@bar.tld'])
+
+In other cases you might notice that some of your emails use common ``template_name``
+and so to save some space you might wish to override the base class' attribute.
+
+.. code-block:: python
+
+    class MyEmailMessage(BaseEmailMessage):
+        template_name = 'email.html'

docs/source/templates_syntax.rst

@@ -0,0 +1,24 @@
+Templates syntax
+================
+
+Email templates can be built using three simple blocks:
+
+- ``subject`` - used for subject of an email message
+- ``text_body`` - used for plaintext body of an email message (not required)
+- ``html_body`` - used for html body of an email message (not required)
+
+Examples
+--------
+
+.. code-block:: html
+
+    {% block subject %}Text and HTML mail subject{% endblock %}
+
+    {% block text_body %}Foobar email content{% endblock %}
+
+.. code-block:: html
+
+    {% block subject %}Text and HTML mail subject{% endblock %}
+
+    {% block text_body %}Foobar email content{% endblock %}
+    {% block html_body %}<p>Foobar email content</p>{% endblock %}