Add document validation for Mongodb 3.6 and later

https://github.com/MyIsaak/sqlitemongo/blob/0307fd374bd4f20f3a57870b95899dc70d3f530a/sqlitemongo.js#L35-L40

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###### This issue was generated by [todo](https://todo.jasonet.co) based on a `TODO` comment in 0307fd374bd4f20f3a57870b95899dc70d3f530a when #4 was merged. cc @MyIsaak.