fix: broken TOC anchor for AI Model and missing Distributed Systems entry

## Bug Report Two bugs found in the Table of Contents of README.md: ### Bug 1: Broken anchor for "AI Model" The TOC entry: ``` * [AI Model](#ai-model) ``` points to `#ai-model`, but the actual section heading is: ``` #### Build your own `AI Model` ``` which generates anchor `#build-your-own-ai-model`. Clicking the TOC link goes nowhere. ### Bug 2: "Distributed Systems" section missing from TOC The README contains a section `#### Build your own \`Distributed Systems\`` (with a tutorial entry) but there is **no corresponding entry in the Table of Contents**, making it invisible to readers navigating via the TOC. ## Fix 1. Change `[AI Model](#ai-model)` → `[AI Model](#build-your-own-ai-model)` 2. Add `* [Distributed Systems](#build-your-own-distributed-systems)` to the TOC (in alphabetical position, between `[Docker]` and `[Emulator / Virtual Machine]`... actually it should go before `[3D Renderer]` alphabetically or at top since it appears first in content) Signed-off-by: cocoon <54054995+kuishou68@users.noreply.github.com>