Orientation to purpose of the different 'sub'-pipelines

[mharms]

It would be helpful to users if we included a general orientation to the purpose of all the different 'sub'-pipelines (i.e., sub-directories in Pipelines directory), either as part of the top-level README, or as part of the FAQ (or updated Release Notes). e.g., something similar to https://wiki.humanconnectome.org/display/PublicData/HCP+Users+FAQ#HCPUsersFAQ-10.Whatistheorderofpipelinesforresting-statedata? but with more detail and guidance.