Multiple schemas in single config

We can declare multiple schemas in the same config. This can be useful for syncing multiple tables into different Elasticsearch indices.

[
    {
        "database": "book",
        "index": "book_index",
        "nodes": [
            {
                "table": "book"
            }
        ]
    },
    {
        "database": "book",
        "index": "author_index",
        "nodes": [
            {
                "table": "author"
            }
        ]
    }
]