Added path fragment prefix

I really like integrating this into our existing spring project, but one thing I wanted was the ability to filter what's returned depending on the root prefix.

For example, my project might have a versioned root, so I might have "/v1/thing" and "/v2/thing". So what this change does now is it allows you make a request like this: "/api-docs?path=v1", and this will return controllerEndpoints which start with `/v1/`.