added init docs (#1167)

docs/sanic/debug_mode.rst

@@ -0,0 +1,53 @@
+Debug Mode
+=============
+
+When enabling Sanic's debug mode, Sanic will provide a more verbose logging output
+and by default will enable the Auto Reload feature.
+
+.. warning::
+
+    Sanic's debug more will slow down the server's performance
+    and is therefore advised to enable it only in development environments.
+
+
+Setting the debug mode
+----------------------
+
+By setting the ``debug`` mode a more verbose output from Sanic will be outputed
+and the Automatic Reloader will be activated.
+
+.. code-block:: python
+
+    from sanic import Sanic
+    from sanic.response import json
+
+    app = Sanic()
+
+    @app.route('/')
+    async def hello_world(request):
+        return json({"hello": "world"})
+
+    if __name__ == '__main__':
+        app.run(host="0.0.0.0", port=8000, debug=True)
+
+
+
+Manually setting auto reload
+----------------------------
+
+Sanic offers a way to enable or disable the Automatic Reloader manually,
+the ``auto_reload`` argument will activate or deactivate the Automatic Reloader.
+
+.. code-block:: python
+
+    from sanic import Sanic
+    from sanic.response import json
+
+    app = Sanic()
+
+    @app.route('/')
+    async def hello_world(request):
+        return json({"hello": "world"})
+
+    if __name__ == '__main__':
+        app.run(host="0.0.0.0", port=8000, auto_reload=True)