Neurodocker tutorial enhancement

[chaselgrove]

From @seanhatton (in the tutorial review sheet), regarding the Neurodocker tutorial:

After Step 4: Building Docker Image it would be helpful to show the command to run the FSL container (e.g. batch file command to run an FSL command on all BIDS folders)

This does not need to be done by our September 15 tutorial deadline.

[memartone]

@djarecka Would you still like to pick this issue up?