docs: update readme with some notes about the version

Author: davidkallesen

README.md

@@ -4,6 +4,12 @@
 
 Common tools for writing tests using XUnit, AutoFixture, NSubstitute and FluentAssertions.
 
+> **Version Notes:**  
+> If you are using the `MemberAutoNSubstituteData` attribute, ensure that both `xunit` and `xunit.extensibility.core` packages are set to version **2.9.0**.
+> This is because the latest versions of xUnit are currently incompatible with `MemberAutoNSubstituteData` due to an unresolved issue. Although [xunit/xunit#3031](https://github.com/xunit/xunit/issues/3031) has been closed, the problem remains unresolved.  
+> Upgrading beyond version 2.9.0 may result in test failures or unexpected behavior.
+
+
 ## Test Attributes
 
 | Name | Description |
@@ -12,7 +18,8 @@ Common tools for writing tests using XUnit, AutoFixture, NSubstitute and FluentA
 | `InlineAutoNSubstituteData` | Provides a data source for a data theory, with the data coming from inline values combined with auto-generated data specimens generated by AutoFixture and NSubstitute.|
 | `MemberAutoNSubstituteData` | Provides a data source for a data theory, with the data coming from one of the following sources and combined with auto-generated data specimens generated by AutoFixture and NSubstitute.|
 
-Note: NSubstitute is used when the type being created is abstract, or when the `[Substitute]` is applied.
+> **Note:**
+> NSubstitute is used when the type being created is abstract, or when the `[Substitute]` is applied.
 
 ## Test Helpers