Fix typo in readme

Author: josesimoes

README.md

@@ -188,7 +188,7 @@ The **nanoFramework** firmware flasher tool is licensed under the [MIT license](
 
 ## Code of Conduct
 
-This project has adopted the code of conduct defined by the Contributor Covenant to clarify expected behavior in our community.
+This project has adopted the code of conduct defined by the Contributor Covenant to clarify expected behaviour in our community.
 For more information see the [.NET Foundation Code of Conduct](https://dotnetfoundation.org/code-of-conduct).
 
 ### .NET Foundation