Remove beta note since generally available

ferhatelmas · mvdan · commit 35a4149b18db · 2020-01-08T07:06:22.000+09:00
diff --git a/README.md b/README.md
@@ -160,7 +160,7 @@ jobs:
 
 ## Quick links
 
-* Concepts, rate limits, joining the beta, etc: https://help.github.com/en/articles/about-github-actions
+* Concepts, rate limits, etc: https://help.github.com/en/articles/about-github-actions
 
 * Syntax and fields reference: https://help.github.com/en/articles/workflow-syntax-for-github-actions
 
