Merge the instructions from lab wiki and github README

[JWinawer]

Currently, we have a summary of this sample data set code in 3 places:

• GitHub README for this repository
• Lab wiki location 1: https://wikis.nyu.edu/display/winawerlab/Sample+Data+Pipeline
• Lab wiki location 2: https://wikis.nyu.edu/display/winawerlab/Running+fMRI+pipeline

We should merge all of this into the README and remove the lab wiki pages (or replace them with a brief summary and a link to the README)

[billbrod]

Also, make sure to update the names of the scripts to reflect the recent name changes (e.g., s4_prf.sh to s4b_analyzePRF.sh)