Modify derivatives softsegs in sb/add_extra_manual_seg

[mguaypaq]

These are the new changes from the branch sb/add_extra_manual_seg, without the conflicts with the master branch. The original PR is at data-management#182.

bids-validator seems reasonably happy about these changes:

$ bids-validator . --config.ignore=38 --config.ignore=39 --config.ignore=101
bids-validator@1.8.9
bids-specification@disable
(node:25037) Warning: Closing directory handle on garbage collection
(Use `node --trace-warnings ...` to show where the warning was created)
This dataset appears to be BIDS compatible.
        Summary:                  Available Tasks:        Available Modalities: 
        2698 Files, 8.51GB                                MRI                   
        267 - Subjects                                                          
        1 - Session                                                             


        If you have any questions, please post on https://neurostars.org/tags/bids.

[sandrinebedard]

@mguaypaq I'll let you merge (or is just using the squash and merge fine here?) Thanks!

[mguaypaq]

Done! And for future work, you can avoid merge conflicts by starting with:

git checkout master
git pull origin
git checkout -b sb/my_new_topic