Update docker-compose.yml

[dborowy]

Leaving the "/" after ":ro" throws out an error when using docker-compose up -d

Description

Fixes #

Type of change

• [ X] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [X ] My code follows the style guidelines of this project
• [ X] I have performed a self-review of my own code
• [ X] I have commented my code, particularly in hard-to-understand areas
• [X ] I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• [X ] If necessary I have added tests that prove my fix is effective or that my feature works
• [ X] New and existing unit tests pass locally with my changes

[polarathene]

Thanks for spotting that! Accident on my part 😬