Add section on how to make changes to the legal docs

README.md

@@ -5,3 +5,9 @@ Legal agreements concerning Arch Linux services and contributions
 - [**Privacy Policy**](privacy-policy.md)
 - [**Terms of Service**](terms-of-service.md)
 - [**Code of Conduct**](code-of-conduct.md)
+
+## Changing these documents
+
+As per our Terms of Service, if we want to make changes to these legal documents, in order for the changes to be
+legally effective, we'll have to announce any changes **at least four weeks** before they become effective.
+The announcement will have to be made directly to every registered user via email.