Update README.rst to show asyncio code (#456)

README.rst

@@ -29,26 +29,30 @@ Creating a client
   phone = '+34600000000'
 
   client = TelegramClient('session_name', api_id, api_hash)
-  client.connect()
-
-  # If you already have a previous 'session_name.session' file, skip this.
-  client.sign_in(phone=phone)
-  me = client.sign_in(code=77777)  # Put whatever code you received here.
+  async def main():
+      await client.connect()
+      # Skip this if you already have a previous 'session_name.session' file
+      await client.sign_in(phone_number)
+      me = await client.sign_in(code=input('Code: '))
 
 
 Doing stuff
 -----------
 
+Note that this assumes you're inside an "async def" method. Check out the
+`Python documentation <https://docs.python.org/3/library/asyncio-dev.html>`_
+if you're new with ``asyncio``.
+
 .. code:: python
 
   print(me.stringify())
 
-  client.send_message('username', 'Hello! Talking to you from Telethon')
-  client.send_file('username', '/home/myself/Pictures/holidays.jpg')
+  await client.send_message('username', 'Hello! Talking to you from Telethon')
+  await client.send_file('username', '/home/myself/Pictures/holidays.jpg')
 
-  client.download_profile_photo(me)
-  total, messages, senders = client.get_message_history('username')
-  client.download_media(messages[0])
+  await client.download_profile_photo(me)
+  total, messages, senders = await client.get_message_history('username')
+  await client.download_media(messages[0])
 
 
 Next steps
@@ -57,4 +61,6 @@ Next steps
 Do you like how Telethon looks? Check the
 `wiki over GitHub <https://github.com/LonamiWebs/Telethon/wiki>`_ for a
 more in-depth explanation, with examples, troubleshooting issues, and more
-useful information.
+useful information. Note that the examples there are written for the threaded
+version, not the one using asyncio. However, you just need to await every
+remote call.