Need sample that shows the installation of additional packages in chiseled scenarios

[mthalman]

Installing additional packages into a chiseled container is not a straightforward task due to the lack of a shell. The only documentation that exists currently which illustrates how to do this is at rockcrafters/dotnet#21 (comment). We should clean that up and include that in our samples.

We then should update the link here to reference this new sample.

[mthalman]

The need for this is exemplified by dotnet/core#8663.

Depending on the outcome of #4804, we should use icu as the example of what to install. If we end up producing images with icu, then that would be irrelevant and can target a different commonly used package instead.

[richlander]

I suggest we disconnect the icu conversation from this one. It's possible that we'll fully cover the ICU space. As you've raised, there is still tzdata and many other libraries that people might want.

I suggest you create a sample for icu and tzdata. That's relevant now. Perhaps, we'll removed icu from it later.

[mthalman]

The documentation should include notes on identifying that the desired package is defined as a slice and using it via chisel. And also handle a scenario where the desired package is not defined as a slice and describe how to include it via regular package installation.