Add articles to the "Learning material" section (#1243)

Author: Clarity-89

docs/learning.mdx

@@ -43,6 +43,9 @@ sidebar_label: Learning Material
   [Daniel Afonso](https://twitter.com/danieljcafonso)
 - [Testing Apollo Components Using react-testing-library](https://www.arahansen.com/testing-apollo-components-using-react-testing-library/)
   by [Andrew Hansen](https://twitter.com/arahansen)
+- [Enzyme vs React Testing Library: A Migration Guide](https://claritydev.net/blog/enzyme-vs-react-testing-library-migration-guide) by [Alex Khomenko](https://claritydev.net)
+- [Testing React Hook Form With React Testing Library](https://claritydev.net/blog/testing-react-hook-form-with-react-testing-library) by [Alex Khomenko](https://claritydev.net)
+- [Improving React Testing Library Tests](https://claritydev.net/blog/improving-react-testing-library-tests) by [Alex Khomenko](https://claritydev.net)   
 
 ## Portuguese 🇧🇷