Update ERP tutorial

[volerina]

those scripts and resources might be useful for restructuring or developing ERP tutorials:

https://github.com/CarinaFo/MNE_workshop_liverpool_2024

[volerina]

Changes/Updates to implement:

• Reformulate goal of the tutorial
• brief description of dataset/paradigm & link to it
• brief reminder that data is already preprocessed, list preproc steps, give links
• pick EEG channels
• update channel names (why are we doing it exactly?)
• plot channels locations: shorten, since description is provided elsewhere, give links to it
• clarify diff btw channel location plots
• clarify that ch highlighted in red is marked as bad
• drop/reword EEG reference section (since data is already re-referenced we don't really need it)
• drop/reword filtering example (since data is already filtered we don't really need it)
• Epoching & averaging section:
  • move dataset description & link to the very top of tutorial
  • revise automatic epoch rejection - shorten?
• Plotting section:
  • subset epochs of interest - i.e., only keep epochs of experimental conditions
  • keep all plot types but update description
  • grand averages - add export/save?
• ERP measures
  • reduce text, add newly implemented ERP measures
  • add export for further stats analyses