[FEATURE] Provide a JSON Schema for sumary.json

[terenc3]

Please provide also a JSON Schema for summary.json so that tools like VSCode can provide autocompletion. Currently i use the following which seems to be okayish.

{
    "fileMatch": [
        "summary.json"
    ],
    "schema": {
        "definitions": {
            "entry": {
                "type": "object",
                "properties": {
                    "title": {
                        "type": "string"
                    },
                    "file": {
                        "type": "string"
                    },
                    "children": {
                        "type": "array",
                        "items": {
                            "$ref": "#/definitions/entry",
                        }
                    }
                }
            }
        },
        "type": "array",
        "items": {
            "$ref": "#/definitions/entry",
        }
    }
}

Related issues

#577