Integration/Embedding Guide & Tools

As a developer or Benefits Analyst
When I want to integrate a BDT screener into my own infrastructure
I should be able to reference documentation for how to do so easily and securely
And be provided tools to make it as simple as possible

Three possible use cases initially:
- Embed a screener on in an existing web page* (provide iframe snippet to copy from existing Publish tab in the web app?)
- Inject starting data (e.g. from a CRM database) into the screener with a custom call to [form-js viewer](https://github.com/CodeForPhilly/benefit-decision-toolkit/pull/285) (or something similar)
- Save the response from the eligibility api to a database/storage system

We could "dog food" these tools by using them to help build #274

*Or maybe embed into Salesforce? (Developer instance of SF + Iframe Embed + LWC Wrapper + postMessage() for data exchange)