148 even more doc updates

[dlebauer]

This PR updates documentation

• splits out model inputs and model outputs sections from parameters.md (fixes Separate file format documentation from parameters.md #99)
• add targets to run unit and smoke tests separately
• fixes Add GH Action to check for broken links in docs #150 by adding GitHub Actions workflow to check for broken links
• update structure in mkdocs.yml
• closes Create coding style doc #121 (should have been previously closed when section on formatting was added to CONTRIBUTING.md)
• update author order to be in line with v 2.0 contributions