{"CodeAdded", "Codelock placed with code {0}. To change your codes use /al your-code."},

or

{"CodeAdded", "Codelock placed with code {0}. For more info use /al"},

I'm confused on what you're asking?

When a new player joins the server and addes a door to there base the annoucment that they get is "Codelock placed with code 1234."

It would be nice if it would also tell them how to change there password.

Somthink like this:

"Codelock placed with code 1234. To change your codes use /al your-code."