(docs) ImageBuilder docs don't provide schema for distribution configurations

### Describe the issue

The docs for `amiDistributionConfiguration` and the `containerDistributionConfiguration` properties reference an example schema on the same page. (It says below, but it's actually above, though that's incidental.) However the schemas for these properties are not documented in that example.

I believe that what's wanted is CfnDistributionConfiguration but this is not clear at all from the example code.

### Links

https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_imagebuilder.CfnDistributionConfiguration.DistributionProperty.html#amidistributionconfiguration

Start with the linked CfnDistributionConfiguration.DistributionProperty API documentation and inspect the descriptions for amiDistributionConfiguration and containerDistributionConfiguration. Clarify which schemas those properties use, making the relationship to CfnDistributionConfiguration explicit; done when the page clearly documents both property schemas.

Written by the indexing model from the issue text.