expose TX_SIMULATE env

Author: wisarmy

.env.example

@@ -22,4 +22,7 @@ JITO_TIP_STREAM_URL=wss://bundles.jito.wtf/api/v1/bundles/tip_stream
 # only support: 25 50 75 95 99
 # ref https://jito-labs.metabaseapp.com/public/dashboard/016d4d60-e168-4a8f-93c7-4cd5ec6c7c8d
 JITO_TIP_PERCENTILE=50
-JITO_TIP_VALUE=          # float64, if set, JITO_TIP_PERCENTILE will be ignored
+# JITO_TIP_VALUE=          # float64, if set, JITO_TIP_PERCENTILE will be ignored
+
+# open simulate mode to see what went wrong
+TX_SIMULATE=false