docs: update docs for Telegram integration

docs/CHEATSHEET.md

@@ -504,6 +504,23 @@ Teams endpoint: `POST /api/messages`. HMAC-SHA256 auth via `Authorization: HMAC
 Replies returned as JSON in HTTP response. IRC-only commands (kick, ban, topic) are no-ops.
 ~90% of plugins work without modification.
 
+## Telegram Integration
+
+```toml
+# config/derp.toml
+[telegram]
+enabled = true
+bot_token = "123456:ABC-DEF..."     # from @BotFather
+poll_timeout = 30                    # long-poll seconds
+admins = [123456789]                 # Telegram user IDs
+operators = []
+trusted = []
+```
+
+Long-polling via `getUpdates` -- no public endpoint needed. All HTTP
+through SOCKS5 proxy. Strips `@botusername` suffix in groups. Messages
+split at 4096 chars. IRC-only commands are no-ops. ~90% of plugins work.
+
 ## Plugin Template
 
 ```python