Small tweaks for the DASCore paper

[d-chambers]

Description

This PR:

• Fixes an issue with the colorbar showing up on the wrong plot for a waterfall plot with multiple panels
• Adds an "example_event_2" which has units set and is filtered for easier viewing.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes.
• documented the new feature with docstrings or appropriate doc page.
• included a test. See testing guidelines.
• your name has been added to the contributors page (docs/contributors.md).
• added the "ready_for_review" tag once the PR is ready to be reviewed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (aa256b2) 99.50% compared to head (7cdccd6) 99.50%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #317   +/-   ##
=======================================
  Coverage   99.50%   99.50%           
=======================================
  Files          89       89           
  Lines        7033     7041    +8     
=======================================
+ Hits         6998     7006    +8     
  Misses         35       35           

Flag	Coverage Δ
unittests	99.50% <100.00%> (+<0.01%)	⬆️

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