Update examples

[m-wierzba]

The previous PR was accidentally merged using push --force. This one continues the work started in the previous one.

[mslw]

I looked at the current state and it looks pretty much as I would imagine it. There is very little, if anything, that would be missing from the narrative.

We spoke off the list and it seems that the main thing missing now is the fMRIPreped dataset to be cloned, which would provide a remake target (in general it would be good to have one, so that the tutorial can be completed without having to go through a full fMRIPrep run first). And this is the only reason for the PR being kept in the draft state. Whoever gets to it first can set it up; I am personally stuck with a provisioning problem for prospective execution (#69 - it seems noone else has experienced it before) and will prioritize understanding what happens there.

[christian-monch]

Nice. There are just two comments that should be addressed before merging (remove the instructions to start the remake-remote).

[christian-monch]

@m-wierzba The current examples will not work because the remote needs a special git configuration to run in untrusted mode. Let's refer to git-documentation on signing and execute everything in trusted mode.

If that seems too complicated: we can do untrusted computation but the user has to add the following key with the value true to his global git configuration (<DATASET-ID> is the id of the dataset on which datalad make is executed):

datalad.make.allow-untrusted-execution.d-<DATASET-ID>