docs: document default password retrieval and custom password usage

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ops4life

README.md

@@ -23,6 +23,29 @@ docker run -it -p 8080:8080 ops4life/code-server:latest
 
 Then open [http://localhost:8080](http://localhost:8080) in your browser.
 
+### Default password
+
+On first run, a config file is written to `/root/.config/code-server/config.yaml` inside the container with an auto-generated password. To retrieve it:
+
+```bash
+docker exec <container_id> cat /root/.config/code-server/config.yaml
+```
+
+The output will contain the password:
+
+```yaml
+bind-addr: 0.0.0.0:8080
+auth: password
+password: <auto-generated>
+cert: false
+```
+
+To set a custom password, pass the `PASSWORD` environment variable:
+
+```bash
+docker run -it -p 8080:8080 -e PASSWORD=yourpassword ops4life/code-server:latest
+```
+
 ## Local build
 
 ```bash