Add YAML Linting

[scottnuma]

• The website utilizes YAML to configure the robot and store data
• YAML is particular about it's formatting, and syntax errors aren't always immediately noticeable
• Add a GitHub Action that will run a YAML linter that will fail if there are any YAML errors
• https://github.com/ibiqlik/action-yamllint has an pre-built Action that we might be able to use, though there may be better candidates, including writing our own custom GitHub Action