Make deprecation notice larger (#1300)

Author: kyu-c

README.md

@@ -5,9 +5,9 @@
 [![Continuous Integration](https://github.com/0xProject/0x-api/workflows/Build%20and%20Test/badge.svg)](https://github.com/0xProject/0x-api/actions?query=workflow%3A%22Build+and+Test%22+branch%3Amaster)
 [![No Maintenance Intended](http://unmaintained.tech/badge.svg)](http://unmaintained.tech/)
 
-⚠️ DEPRECATION NOTICE ⚠️
+# ⚠️ DEPRECATION NOTICE ⚠️
 
-This repository is no longer maintained by the 0x team. It will remain available for download and use, but we will not be providing any further support
+This repository is no longer maintained by the 0x team. It will remain available for download and use, but we will not be providing any further support.
 For more information please see [our blog post](https://blog.0x.org/0x-protocol-a-preview-of-whats-to-come/).
 
 If you are looking to access Swap API, please contact the 0x team via the contact form in [0x.org](https://0x.org).