[FIX] Fix typos in specification about iEEG photo

[qian-chu]

In the example:

1. Modality ieeg was missing from the filetree
2. sub and ses in the photo prefix didn't match the actual names
3. Remove unintended break

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.07%. Comparing base (44d8461) to head (2a436d7).
Report is 181 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2091   +/-   ##
=======================================
  Coverage   83.07%   83.07%           
=======================================
  Files          17       17           
  Lines        1524     1524           
=======================================
  Hits         1266     1266           
  Misses        258      258           

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[effigies]

LGTM. Thanks!

[qian-chu]

Does anyone else want to take a look at the correction? Thanks!
(PS Error seems to come from an unrelated link issue shared with other PRs.)

[effigies]

I think we should proceed by lazy consensus here, as this is a minor fix, not a new feature. I'm going to waive the second review requirement and merge, but others should feel free to back this out if it turns out they disagree.