Improve documentation on recipe files

[robertlugg]

I want to understand the difference between "recipe files" and "module files"

I believe the differences are described here

But there isn't much detail. What is the difference between code written as a recipe and code written as a module? I can guess at a few. But, for instance, does the hpccm tool auto import hpccm before loading the recipe files?

[samcmill]

The hpccm CLI tool imports the hpccm module and provides some other boilerplate. See hpccm/cli.py. The CLI tool can save some time and effort in most cases.

However, if you want to customize the behavior or have a "standalone" script that does not require processing by the CLI tool, then you can use the hpccm module in your own Python script. The Jupyter notebook sample does this (recipes/jupyter) in order to add some custom command line options (--notebook, --requirements, etc.).