Tidy up deprecation warning

Author: WhyNotHugo

README.rst

@@ -17,12 +17,12 @@ django-mercadopago
   :target: https://github.com/WhyNotHugo/django-mercadopago/blob/master/LICENCE
   :alt: licence
 
-**THIS LIBRARY IS UNMAINTAINED**
+** ⚠️ THIS LIBRARY IS DEPRECATED**
 
 We've merged our code into `django-payments <https://github.com/jazzband/django-payments>`_.
 It has a cleaner API, and supports several other payment providers under the hood.
 
-It's recommended that you use that library instead.
+It is recommended that developers use that library instead of this one.
 
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