ensure message vars in template strings are not interpolated in shell/env

Author: FlorianSW

.env.example

@@ -50,5 +50,5 @@ DISCORD_MESSAGE_CHANNEL_ID=
 #  - queuedPlayersMessage: The message as defined in DISCORD_PUBLISHER_MESSAGE_QUEUED_FORMAT (only makes sense when the server supports a player queue
 #  - queuedPlayers: The number of players currently in the queue
 # Example (uncomment if editing):
-# DISCORD_PUBLISHER_MESSAGE_FORMAT=${playerCount}/${maxPlayers} ${queuedPlayersMessage}
-# DISCORD_PUBLISHER_MESSAGE_QUEUED_FORMAT=(+${queuedPlayers})
+# DISCORD_PUBLISHER_MESSAGE_FORMAT='${playerCount}/${maxPlayers} ${queuedPlayersMessage}'
+# DISCORD_PUBLISHER_MESSAGE_QUEUED_FORMAT='(+${queuedPlayers})'