doc: clarify env variable

Author: hb9cwp

env.example

@@ -145,7 +145,7 @@ ETHERPAD_SKIN_VARIANTS=super-light-toolbar super-light-editor light-background f
 # Application identifier
 #JWT_APP_ID=my_jitsi_app_id
 
-# Application secret known only to your token
+# Application secret known only to your token generator
 #JWT_APP_SECRET=my_jitsi_app_secret
 
 # (Optional) Set asap_accepted_issuers as a comma separated list