Update tutorial for new bidsapp

[pvandyken]

Changes the final step of the tutorial to use the new bidsapp syntax. fwhm is brought in a specific example for the way CLI arguments can be created.

Still sparse on details for what bidsapp.app actually does and how it can be used. This will come with time.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.49%. Comparing base (d7e5748) to head (4c3a623).

❗ Current head 4c3a623 differs from pull request most recent head 1ce4bfc. Consider uploading reports for the commit 1ce4bfc to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #408   +/-   ##
=======================================
  Coverage   94.49%   94.49%           
=======================================
  Files          55       55           
  Lines        2180     2180           
=======================================
  Hits         2060     2060           
  Misses        120      120           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.