Account for Discord embed character limits

[KevinPayravi]

Discord embed fields have a character limit of 1,024. If a wiki has Cargo tables with long names, it's possible that the payload's list of tables becomes too long, causing Discord to return a 400 error when POSTing the embed.

As the script iterates over each table, it should check to make sure the list's char limit won't be exceeded if the table name is added to it. If it is, the script should stop adding to the list + add a note that the list has been truncated.