Added documentation for AF_INET6 and AF_UNIX socket usage

docs/index.rst

@@ -21,6 +21,7 @@ Guides
    sanic/streaming
    sanic/class_based_views
    sanic/custom_protocol
+   sanic/sockets
    sanic/ssl
    sanic/logging
    sanic/testing

docs/sanic/sockets.rst

@@ -0,0 +1,66 @@
+Sockets
+=======
+
+Sanic can use the python
+`socket module <https://docs.python.org/3/library/socket.html>`_ to accommodate
+non IPv4 sockets.
+
+IPv6 example:
+
+.. code:: python
+
+    from sanic import Sanic
+    from sanic.response import json
+    import socket
+
+    sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
+    sock.bind(('::', 7777))
+
+    app = Sanic()
+
+
+    @app.route("/")
+    async def test(request):
+        return json({"hello": "world"})
+
+    if __name__ == "__main__":
+        app.run(sock=sock)
+
+to test IPv6 ``curl -g -6 "http://[::1]:7777/"``
+
+
+UNIX socket example:
+
+.. code:: python
+
+    import signal
+    import sys
+    import socket
+    import os
+    from sanic import Sanic
+    from sanic.response import json
+
+
+    server_socket = '/tmp/sanic.sock'
+
+    sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    sock.bind(server_socket)
+
+    app = Sanic()
+
+
+    @app.route("/")
+    async def test(request):
+        return json({"hello": "world"})
+
+
+    def signal_handler(sig, frame):
+            print('Exiting')
+            os.unlink(server_socket)
+            sys.exit(0)
+
+
+    if __name__ == "__main__":
+        app.run(sock=sock)
+
+to test UNIX: ``curl -v --unix-socket /tmp/sanic.sock http://localhost/hello``