Add Dev Instructions for Updating Workflow Schema

[grant]

There should instructions for how to update a schema when developing (in VS Code).

Example settings:

"json.schemas": [
        {
            "name": "workflows.json",
            "description": "Google Cloud Workflows configuration file",
            "fileMatch": [
                "workflows.json",
                "*.workflows.json",
            ],
            "url": "https://json.schemastore.org/workflows"
          }
    ],
    "yaml.schemas": {
        "https://json.schemastore.org/workflows": [
            "workflows.yaml",
            "workflows.yml",
            "*.workflows.yaml",
            "*.workflows.yml"
        ]
    },