docs(docker): add bind mount example to persist GitHub token in Docker container

- Show how to mount a host directory to /root/.local/share/copilot-api for token persistence
- Add explanation and note for clarity

🤖 Generated with [opencode](https://opencode.ai)

Co-Authored-By: opencode <noreply@opencode.ai>

Author: ericc-ch

README.md

@@ -54,9 +54,18 @@ docker build -t copilot-api .
 Run the container
 
 ```sh
-docker run -p 4141:4141 copilot-api
+# Create a directory on your host to persist the GitHub token and related data
+mkdir -p ./copilot-data
+
+# Run the container with a bind mount to persist the token
+# This ensures your authentication survives container restarts
+
+docker run -p 4141:4141 -v $(pwd)/copilot-data:/root/.local/share/copilot-api copilot-api
 ```
 
+> **Note:**
+> The GitHub token and related data will be stored in `copilot-data` on your host. This is mapped to `/root/.local/share/copilot-api` inside the container, ensuring persistence across restarts.
+
 ### Docker with Environment Variables
 
 You can pass the GitHub token directly to the container using environment variables: