Full documentation missing from CloudFront event type

Bug Report

Description

The documentation for cloudfront is very thin (https://serverless.com/framework/docs/providers/aws/events/cloudfront/). There's a few examples, but there's no complete documentation of all supported params. Since its likely that users have to use a Resources object to describe the Cloudfront distribution in detail, this event type is potentially quite complex to get right. It would be good of the documentation was a bit richer.

For example, there's no mention of the fact that CustomOriginConfig is a required field if using non-s3 origins.

As an example: I notice that in code, the QueryString attribute is hard-coded to false (https://github.com/serverless/serverless/blob/c0ec32b4e0f2e3dacce12a614db92dfba6e526a6/lib/plugins/aws/package/compile/events/cloudFront/index.js#L181), which means that I probably have to "overwrite" the entire origin attribute. I'm suspecting this is quite common for uses-cases where cloudfront/lambda@edge is involved so it would be good if that was documented.
In short: Make it as easy as possible to get cloudfront/lambda@edge right using serverless - also for non-trivial/real-life apps.

Start with the CloudFront documentation page and the AWS CloudFront compiler at lib/plugins/aws/package/compile/events/cloudFront/index.js, especially the QueryString handling. Compare the supported event parameters with the current examples, then document non-S3 CustomOriginConfig requirements and how origin settings are overridden for CloudFront and Lambda@Edge use cases.