[ChangeLog] typo fix

Author: glessard

CHANGELOG.md

@@ -128,7 +128,7 @@ _**Note:** This is in reverse chronological order, so newer entries are added to
 
   Distributed actors provide stronger isolation guarantees than "local" actors, and enable additional checks to be made on return types and parameters of distributed methods, e.g. checking if they conform to `Codable`. Distributed methods can be called on "remote" references of distributed actors, turning those invocations into remote procedure calls, by means of pluggable and user extensible distributed actor system implementations. 
 
-  Swift does not provide any specific distributed actor system by itself, however, packages in the ecosystem fulfil the role of providing those implementations.
+  Swift does not provide any specific distributed actor system by itself, however, packages in the ecosystem fulfill the role of providing those implementations.
 
   ```swift
   distributed actor Greeter {