Docs: update plot_butterfly docs

[behinger]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (23de34e) 84.28% compared to head (a49acef) 84.28%.
Report is 28 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #119   +/-   ##
=======================================
  Coverage   84.28%   84.28%           
=======================================
  Files          17       17           
  Lines         611      611           
=======================================
  Hits          515      515           
  Misses         96       96           

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

[vladdez]

1. Should be:
   "provide 2D layout positions to add an inset based on channel location and color the lines in a logical way."
   Lowercase and comma at the end.
   But I would write: "add an inset with channel layout with colors corresponding with lines.".
2. what the difference between? Are they both change erp plot to butterfly plot? What "Internal" means?

• positions (nothing): see plot_butterfly.
  Internal:
• butterfly (bool, true): a butterfly plot.

3. As is understood "positions" add topoplot, Why not to call it "add_topoplot" or "add_layout"? Otherwise it is not obvious what this arguments does.

[behinger]

1. I rephrased it again.
2. I dont understand your comment. can you rephrase?
3. topolegend already exists which is exactly what you propose. But you might want to have position-wise colors, but not the topoinset, so both are neede