Consider adding container information to build table

The [build table](https://github.com/dotnet/installer#installers-and-binaries) includes information for multiple information types, but not container images. Container images would likely be more popular than some of the download types listed. We should consider adding container information.

The challenge is that we don't build container images for every branch. As a result, we'd need to come up with a predictable scheme for the table.

@MichaelSimons, @mthalman, @dleeapho