Help and docs for the new commands

- /help is sent as a few messages (Discord caps an embed at 6000 characters), with a test for the limits
- command reference, features, self-hosting, beta and getting-started pages describe the commands; the SQL section is gone
- development and contributing: every setting needs a command

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

docs/development.md

@@ -190,7 +190,9 @@ added, err := services.Global.Meeting.AddLobby(ctx, guildID, channelID)
 
 **6. Enforce limits in the database when you can.** The 10-lobby limit is a trigger, so the bot and anything else writing to the table cannot disagree and two simultaneous requests cannot both slip through.
 
-**7. Default to off.** A module that does something to a server without being asked (posts messages, moderates, grants roles) must start disabled and be turned on by an admin.
+**7. Give it commands.** Every setting must be visible and changeable from Discord (a slash command to set it, and a way to see it). The bot has to work completely without a dashboard, so never add a setting that only a dashboard or SQL can change. Put the options in the command definition, and `internal/commands/limits_test.go` will tell you if it goes over Discord's limits.
+
+**8. Default to off.** A module that does something to a server without being asked (posts messages, moderates, grants roles) must start disabled and be turned on by an admin.
 
 ## React to a gateway event