Add xl, 2xl, and 3xl border radius values (#2529)

Author: adamwathan

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add new `presets` config option ([#2474](https://github.com/tailwindlabs/tailwindcss/pull/2474))
 - Make `outline` configurable, `outline-none` more accessible by default, and add `outline-black` and `outline-white` ([#2460](https://github.com/tailwindlabs/tailwindcss/pull/2460))
 - Add additional small `rotate` and `skew` values ([#2528](https://github.com/tailwindlabs/tailwindcss/pull/2528))
+- Add `xl`, `2xl`, and `3xl` border radius values ([#2529](https://github.com/tailwindlabs/tailwindcss/pull/2529))
 
 ## [1.8.12] - 2020-10-07