Correct docker/README.md: documented volumes and services that do not exist

docker/README.md

@@ -15,7 +15,7 @@ OPENAI_API_KEY=sk-...
 
 2. Build and run:
 ```bash
-docker-compose up --build
+docker compose up --build
 ```
 
 3. Access:
@@ -27,9 +27,48 @@ docker-compose up --build
 
 - **api**: FastAPI backend (port 8000)
 - **web**: Next.js frontend (port 3000)
+- **redis**: cache and rate-limit backend (port 6379). `api` declares
+  `depends_on: redis`, so it is not optional under compose.
+
+Note that redis is published on 6379 with no password. That is fine on a laptop;
+do not expose it on a shared or public host.
 
 ## Data Persistence
 
-Data is stored in Docker volumes:
-- `api-data`: Database and ChromaDB
-- `repos-data`: Cloned repositories
+The `api` service **bind-mounts** the repo's `data/` directory:
+
+```
+../data  ->  /app/data
+```
+
+So the SQLite database, the ChromaDB directory and every cloned repository live in
+`data/` in your working tree, not in a Docker-managed volume, and they survive
+`docker compose down`. Two consequences worth knowing:
+
+- The container runs as root, so files it creates under `data/` are root-owned on
+  the host.
+- `docker-compose.yml` also declares a named volume `data:` that nothing mounts.
+  It has no effect; the bind mount above is what is actually used.
+
+## Using Ollama from inside Docker
+
+`OLLAMA_BASE_URL` defaults to `http://localhost:11434`, which is correct when you
+run the API directly on your machine but **wrong inside a container** — there,
+`localhost` is the container itself, not your host. If you set
+`LLM_PROVIDER=ollama` or `EMBEDDING_PROVIDER=ollama` in `docker/.env`, also set:
+
+```bash
+OLLAMA_BASE_URL=http://host.docker.internal:11434
+```
+
+On Docker Desktop (macOS/Windows) that name resolves automatically. On Linux it
+does not unless you add it to the `api` service:
+
+```yaml
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+```
+
+Also pull the model first (`ollama pull nomic-embed-text`) — a missing model now
+fails fast with a clear error rather than embedding your whole repository as zero
+vectors.