command: explain - show recipes documentation

[jmoalves]

We should provide a command:

levain explain <recipe> <recipe>

The main purpose is to unlock the user from levain.

The command should create a markdown with the actions performed by a recipe and its dependencies in the proper order.

This markdown could work as a documentation script on how to perform the actions manually.

In a first approach, we could write the actions with the variable substitutions for the recipe, following its dependencies in order.

TODO

• [ ] Replace vars
• [ ] Handle some actions the change vars (like setVar, setEnv)

[jmoalves]

Perhaps it would be easier if we had a common place to "compile" the recipes. I mean, to read the recipes, follow the dependencies, replace variables, and so on.

Including a complete suggestion at issue #75.