Update max Twitter characters to 280
Twitter expanded the maximum character count per tweet from 140 to 280 in November 2017.
@@ -18,7 +18,7 @@ and use the tag ``python-requests``.
Send a Tweet
------------
-If your question is less than 140 characters, feel free to send a tweet to
+If your question is less than 280 characters, feel free to send a tweet to
`@kennethreitz <https://twitter.com/kennethreitz>`_,
`@sigmavirus24 <https://twitter.com/sigmavirus24>`_, or
`@lukasaoz <https://twitter.com/lukasaoz>`_.
