Add VS canton email configuration to environment example

Author: Michael-Schaer

.env.example

@@ -78,3 +78,4 @@ CANTON_EMAIL_BE="test-be@example.com"
 # CANTON_EMAIL_NE="ne@example.com"
 # CANTON_EMAIL_GE="ge@example.com"
 # CANTON_EMAIL_JU="ju@example.com"
+# CANTON_EMAIL_VS="vs@example.com"