update extracellular electrophysiology tutorial

[stephprince]

Motivation

Update some of the recently added examples in the extracellular ephys tutorial and address nwbinspector warnings.

• fix [Documentation]: Update text describing LFP and FilteredEphys in ecephys tutorial. #2005
• fix [Documentation]: Update DecompositionSeries example for schema v2.8.0 #1999

Checklist

• Did you update CHANGELOG.md with your changes?
• Have you checked our Contributing document?
• Have you ensured the PR clearly describes the problem and the solution?
• Is your contribution compliant with our coding style? This can be checked running ruff check . && codespell from the source directory.
• Have you checked to ensure that there aren't other open Pull Requests for the same change?
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.69%. Comparing base (2c2bc85) to head (70780fa).
Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #2012   +/-   ##
=======================================
  Coverage   91.69%   91.69%           
=======================================
  Files          27       27           
  Lines        2708     2708           
  Branches      707      707           
=======================================
  Hits         2483     2483           
  Misses        149      149           
  Partials       76       76           

Flag	Coverage Δ
integration	72.82% <ø> (ø)
unit	82.64% <ø> (ø)

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[stephprince]

@ehennestad I updated the text based on your suggestions and referencing the latest matnwb tutorials - let me know if you had any other suggestions!