Enhance documentation for commands by including which configuration is utilized by the command

[lpeabody]

One of the annoying things about Acquia's BLT is that there was this massive configuration file with seemingly limitless options, and the configuration could be used by any command, but it was not clear what command used what configuration. This made it hard to understand how the behaviors of commands could be affected by configuration, and thus made it harder to learn about how to manipulate, customize, and leverage BLT to its fullest extent.

For example, the artifact:deploy command leverages the configuration value deploy.exclude_file. This would be listed on the documentation page for the artifact:deploy command and describe it's role in the command. This will significantly improve folks' understanding of what the commands are doing and how to shape the behavior of the commands by setting or overriding configuration values.

[lpeabody]

I think in order to have this mechanism work reasonably, every command needs to define what configuration it will deterministically invoke. Maybe there is a way to handle this dynamically via static analysis, but an interim solution could be to use something like attributes to signal if a method invokes configuration. There also needs to be a mechanism that describes what the value is for a given configuration key. If these two pieces are available, then we can reliably generate documentation that explains how the configuration is used and where it's used (i.e. how it might affect the behavior depending on where it's used).

Going to deprioritize for now, but this will be a very useful bit of information for users and developers to have at their disposal.