add comment about adventure version

Author: Derkades

pom.xml

@@ -14,7 +14,7 @@
 		<checkerFrameworkVersion>3.54.0</checkerFrameworkVersion>
 		<velocityVersion>3.4.0</velocityVersion>
 		<bStatsVersion>3.2.1</bStatsVersion>
-		<adventureVersion>4.26.1</adventureVersion>
+		<adventureVersion>4.26.1</adventureVersion> <!-- v5 requires JDK 21, we currently require 11 -->
 	</properties>
 
 	<modules>