env: add note about JaaS account creation

env.example

@@ -43,6 +43,7 @@ TZ=UTC
 #
 
 # Enable JaaS Components (hosted Jigasi)
+# NOTE: if Let's Encrypt is enabled a JaaS account will be automatically created, using the provided email in LETSENCRYPT_EMAIL
 #ENABLE_JAAS_COMPONENTS=0
 
 #