Explain the "pipeline" formed by chaining the tools

[twelho]

As noted in #5, an explanation on how the tools in this repository can be chained (evaluator -> parser -> classifier -> <ordering tool> -> <visualization/BOM tool>) to form what has unofficially been called the "pipeline" is very much necessary to have in the README (and maybe a separate detailed document as well). A supportive visualization using the diagrams.net rendering integration would also be very helpful, with the format of the data (e.g. KiCad schematic, YAML file, Markdown document) visible between each stage.