Fmriprep: improve ICA-AROMA documentation

[jdkent]

Make the process for ICA-AROMA clearer. Ex. what was done to the data before being passed through ICA-AROMA, what was done to the data after ICA-AROMA, and how does ICA-AROMA relate to the other confounds generated.

sources to pull from

• effigies comment
• jdkent comment
• neurostars post

[jdkent]

Also this section is out of date (using fmriprep outputs from before 1.2.0)

pointed out on neurostars

[oesteban]

@jdkent has this been addressed?

[jdkent]

not entirely yet no.

[FL33TW00D]

Another helpful source:
https://sarenseeley.github.io/BIDS-fmriprep-MRIQC.html#are_confounds_in_the_confoundstsv_file_generated_after_ica-aroma_or_before