Update README.md to adequately reflect the specification of an outputs node in the manifest to match the instructions int he readme.

[heaversm]

An "outputs" node in the initialize section of the manifest is needed if you want to see anything in the output directory specified in the readme.

Types of changes

• [ ] Enhancement (project structure, spelling, grammar, formatting)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

A description of the changes proposed in the Pull Request

[heaversm]

This needs to occur for any plugin (for example, e-mem is also missing this).