chore: add comment for init to be removed

app/e2e_include_upgrades.go

@@ -6,6 +6,8 @@ import (
 	"github.com/babylonlabs-io/babylon/app/upgrades/signetlaunch"
 )
 
+// init is used to include signet upgrade used for e2e testing
+// this file should be removed once the upgrade testing with signet ends.
 func init() {
 	Upgrades = append(Upgrades, signetlaunch.Upgrade)
 }