hint to correct jar version in registry extraction script

Author: p2r3

extract_registries.sh

@@ -36,8 +36,8 @@ prepare_notchian_dir() {
 dump_registries() {
   if [[ ! -f "$SERVER_JAR" ]]; then
     echo "No server.jar found (looked for $SERVER_JAR)."
-	echo "Please download the server.jar from https://www.minecraft.net/en-us/download/server"
-	echo "and place it in the notchian directory."
+	echo "Please download the 1.21.8 server.jar (e.g. from https://mcversions.net/download/1.21.8)"
+	echo "and place it in the \"notchian\" directory."
     exit 1
   fi