TOC inside the docs

docs/OTA.md

@@ -6,6 +6,26 @@ The client runs checks and downloads in **`OtaUpdateService`** (a standalone `Se
 
 MQTT is fully supported for OTA sources using retained topic payloads (`mqtt://...` / `mqtts://...`). The URI path is treated as the exact topic to subscribe.
 
+---
+
+## Table of contents
+
+<!-- toc -->
+- [URL layout](#url-layout)
+- [Versioning](#versioning)
+- [JSON files](#json-files)
+- [Optional HTTP bundle (.otabundle.zip)](#optional-http-bundle-otabundlezip)
+- [MQTT transport](#mqtt-transport)
+- [Publish from a release APK](#publish-from-a-release-apk)
+  - [Docker build + staging channel](#docker-build-staging-channel)
+- [App configuration](#app-configuration)
+- [Checklist](#checklist)
+<!-- /toc -->
+
+**Documentation index:** [README.md](README.md)
+
+---
+
 ## URL layout
 
 ```text