Add a FAQ page to documentation

[mattcieslak]

Some common questions would be

• "I just want a connectivity matrix, do I need to use XCP-D?"

[tsalo]

1. I just want to denoise my resting-state data. Should I use XCP-D?
   • A: No, use nilearn.
2. I just want to get ReHo or ALFF from my processed data. Should I use XCP-D?
   • A: No, use AFNI.
3. I just want to parcellate my processed data. Should I use XCP-D?
   • A: No, but XCP-D does do some useful stuff to account for poor parcel coverage.
4. I want to analyze task fMRI data. Should I use XCP-D?
   • A: Not unless you want to pretend the data are resting-state.
5. Stuff about interpolated data. E.g., "are the correlation matrices calculated from the interpolated data?", "should I use the interpolated data in my analyses?"