No-SQL data store

### Required Terms

- [X] I agree to follow this project's [Code of Conduct](https://github.com/heroku/roadmap/blob/main/CODE_OF_CONDUCT.md)
- [X] I have read and accept the [Salesforce Program Agreement](https://www.salesforce.com/company/program-agreement/)

### What service(s) is this request for?

No-SQL Data Add-on

### Tell us about what you're trying to solve. What challenges are you facing?

The lack of a No-SQL data store means developers cannot create MERN stack applications. One big advantage of using a No-SQL data store like MongoDB is being able to define the schema on write. This reduces effort as developers do not need to create database migrations, just define the schema and write to the data store.