clarify prerequisites
diff --git a/README.md b/README.md
index b35afdb..338513d 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,8 @@
 
 ## Rules
 
+**Prerequisites:** `maven-enforcer-plugin` 3.0.0 or newer
+
 ### Require Provided Dependencies in Runtime Classpath (since version 1.0.0)
 
 Checks that the runtime classpath (e.g. used by Maven Plugins via the