Update README.md (kgrzybek#190)

Small typo

README.md

@@ -858,7 +858,7 @@ public async Task<IActionResult> ProposeMeetingGroup(ProposeMeetingGroupRequest
 **Attributes of good unit test**
 
 - Automated
-- Maitainable
+- Maintainable
 - Runs very fast (in ms)
 - Consistent, Deterministic (always the same result)
 - Isolated from other tests
@@ -2002,4 +2002,4 @@ The project is under [MIT license](https://opensource.org/licenses/MIT).
 - ["Hands-On Domain-Driven Design with .NET Core: Tackling complexity in the heart of software by putting DDD principles into practice"](https://www.amazon.com/Hands-Domain-Driven-Design-NET-ebook/dp/B07C5WSR9B) book, Alexey Zimarev
 - ["Versioning in an Event Sourced System"](https://leanpub.com/esversioning) book, Greg Young
 - [Hands-On-Domain-Driven-Design-with-.NET-Core](https://github.com/PacktPublishing/Hands-On-Domain-Driven-Design-with-.NET-Core) GH repository, Alexey Zimarev
-- [EventSourcing.NetCore](https://github.com/oskardudycz/EventSourcing.NetCore) GH repository, Oskar Dudycz
+- [EventSourcing.NetCore](https://github.com/oskardudycz/EventSourcing.NetCore) GH repository, Oskar Dudycz