[RateLimiter][Runtime] Remove experimental from README.md

Author: Jean-Beru

README.md

@@ -3,11 +3,6 @@ Runtime Component
 
 Symfony Runtime enables decoupling applications from global state.
 
-**This Component is experimental**.
-[Experimental features](https://symfony.com/doc/current/contributing/code/experimental.html)
-are not covered by Symfony's
-[Backward Compatibility Promise](https://symfony.com/doc/current/contributing/code/bc.html).
-
 Resources
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