Fix discord url link message (#5079)

Author: JRoy

Essentials/src/main/resources/messages.properties

@@ -253,7 +253,7 @@ discordCommandListArgumentGroup=A specific group to limit your search by
 discordCommandMessageDescription=Messages a player on the Minecraft server.
 discordCommandMessageArgumentUsername=The player to send the message to
 discordCommandMessageArgumentMessage=The message to send to the player
-discordErrorCommand=You added your bot to your server incorrectly. Please follow the tutorial in the config and add your bot using https://essentialsx.net/discord.html!
+discordErrorCommand=You added your bot to your server incorrectly! Please follow the tutorial in the config and add your bot using https://essentialsx.net/discord.html
 discordErrorCommandDisabled=That command is disabled!
 discordErrorLogin=An error occurred while logging into Discord, which has caused the plugin to disable itself: \n{0}
 discordErrorLoggerInvalidChannel=Discord console logging has been disabled due to an invalid channel definition! If you intend to disable it, set the channel ID to "none"; otherwise check that your channel ID is correct.