Fix docker usage readme

[pkqs90]

Background

Since Dockerfile uses /home/appuser as workdir, the mounted volume should also be /home/appuser, or else we can't persist the written files.

https://github.com/Significant-Gravitas/Auto-GPT/blob/master/Dockerfile#L25

Changes

Documentation

Test Plan

Tested locally.

PR Quality Checklist

• [x] My pull request is atomic and focuses on a single change.
• [x] I have thoroughly tested my changes with multiple different prompts.
• [x] I have considered potential risks and mitigations for my changes.
• [x] I have documented my changes clearly and comprehensively.
• [x] I have not snuck in any "extra" small tweaks changes

[hdkiller]

The docker image in latest master in deed uses that workdir.

=> CACHED [ 7/11] WORKDIR /home/appuser                                                                                                                                                        ```

[np]

LGTM. There are two more occurrences of /app in docker-compose.yml.

[pkqs90]

LGTM. There are two more occurrences of /app in docker-compose.yml.

Updated