chore: add copyright header

Remove the async naming rule as the tooling does not really work out to detecting the right usage of the `Async` suffix.

README.md

@@ -1,7 +1,7 @@
 # `Geekeey.Extensions.Result`
 
-Result is a .NET library which provides a Result<T> type for representing the outcome of operations in C#. It offers a
-clean and concise way to handle success and failure scenarios, promoting better error handling and code readability.
+A .NET library provides a Result<T> type for representing the outcome of operations in C#. It offers a clean and concise
+way to handle success and failure scenarios, promoting better error handling and code readability.
 
 ## Features
 
@@ -68,4 +68,4 @@ _ = await Prelude.Try(() => File.ReadAllLines("i_do_not_exist.txt"))
 		var results = await Task.WhenAll(list.Select(DoSomeThing).ToArray());
 		return results.Join();
 	});
-```
+```