Merge pull request #555 from bothzoli/fix/add-ierror-of-string-to-result

Add IError<string> to the Result struct

CSharpFunctionalExtensions/Result/Result.cs

@@ -5,7 +5,7 @@
 namespace CSharpFunctionalExtensions
 {
     [Serializable]
-    public readonly partial struct Result : IResult, ISerializable
+    public readonly partial struct Result : IResult, ISerializable, IError<string>
     {
         public bool IsFailure { get; }
         public bool IsSuccess => !IsFailure;