Adds a secondary username to a bot. Can be called only if userTypeBot.can_be_edited, the bot has no secondary username
and the current user has Telegram Premium subscription. May return an error with a message
"OWNER_USERNAMES_LIMIT_EXCEEDED" if the current user already owns at least getOption("secondary_bot_username_count_max")
bots with a secondary username.
Request type for Tdjson#addBotSecondaryUsername.
Adds a secondary username to a bot. Can be called only if userTypeBot.can_be_edited, the bot has no secondary username and the current user has Telegram Premium subscription. May return an error with a message "OWNER_USERNAMES_LIMIT_EXCEEDED" if the current user already owns at least getOption("secondary_bot_username_count_max") bots with a secondary username. Request type for Tdjson#addBotSecondaryUsername.