Update AV1020 guideline (#350)

Split from #298.

Co-authored-by: Dennis Doomen <dennis.doomen@greenchoice.nl>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people

_rules/1020.md

@@ -6,4 +6,4 @@ severity: 1
 ---
 This means that two classes know about each other's public members or rely on each other's internal behavior. Refactoring or replacing one of those classes requires changes on both parties and may involve a lot of unexpected work. The most obvious way of breaking that dependency is to introduce an interface for one of the classes and using Dependency Injection.
 
-**Exception:** Domain models such as defined in [Domain-Driven Design](http://domaindrivendesign.org/) tend to occasionally involve bidirectional associations that model real-life associations. In those cases, make sure they are really necessary, and if they are, keep them in.
+**Exception:** Domain models such as defined in [Domain-Driven Design](https://en.wikipedia.org/wiki/Domain-driven_design) tend to occasionally involve bidirectional associations that model real-life associations. In those cases, make sure they are really necessary, and if they are, keep them in.