add BATCH_PEER_UPDATE in netmaker.env with default values

scripts/netmaker.default.env

@@ -86,4 +86,8 @@ EMAIL_SENDER_ADDR=
 EMAIL_SENDER_USER=
 # sender smtp password
 EMAIL_SENDER_PASSWORD=
+# if batch peer update enable or not
+PEER_UPDATE_BATCH=true
+# batch peer update size when PEER_UPDATE_BATCH is enabled
+PEER_UPDATE_BATCH_SIZE=50