Update PyMISP_tutorial.ipynb

[ghost]

The function to collect event_id and put it into a list isn't looking into each MISPAttribute.
Just updated the script to look at it and added a description to what it's doing.

[codecov]

Codecov Report

Merging #383 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #383   +/-   ##
=======================================
  Coverage   51.89%   51.89%           
=======================================
  Files          34       34           
  Lines        6403     6403           
=======================================
  Hits         3323     3323           
  Misses       3080     3080

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[coveralls]

Coverage remained the same at 51.898% when pulling 47729c4 on hackunagi:master into 582dda0 on MISP:master.

[coveralls]

Coverage remained the same at 51.898% when pulling 47729c4 on hackunagi:master into 582dda0 on MISP:master.

[coveralls]

Coverage remained the same at 51.898% when pulling 47729c4 on hackunagi:master into 582dda0 on MISP:master.

[adulau]

Thank you!