Add Markdown Linting

[kjaymiller]

Our markdown files are not linted. This means that we can bad formatting and other issues that are not caught by the build process. We should add a markdown linter to our build process.

We can lint via pre-commit. There is a tool call markdownlint-cli that is used by pre-commit and VS Code. We can add a pre-commit hook and use the same config build process that will lint our markdown files.

Steps

• Add markdownlint-cli to devcontainer
• Add markdownlint-cli to pre-commit
• Add .markdownlint.json to root and the projectpath