Getting started: show fiber direction instead of reference direction

[greschd]

Plot the fiber_direction instead of reference_direction in the getting started, to match the text description.

25R2 hardening item 35.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.91%. Comparing base (d9106e3) to head (ec9655b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #816   +/-   ##
=======================================
  Coverage   94.91%   94.91%           
=======================================
  Files         109      109           
  Lines        5737     5737           
  Branches      328      328           
=======================================
  Hits         5445     5445           
  Misses        291      291           
  Partials        1        1           

Flag	Coverage Δ
direct-launch	91.42% <ø> (ø)
minimum-deps	93.07% <ø> (ø)
python-3.10	94.12% <ø> (ø)
python-3.11	94.05% <ø> (ø)
python-3.12	94.26% <ø> (ø)
server-2024R2	90.62% <ø> (ø)
server-2025R1	94.00% <ø> (ø)
server-2025R2	94.05% <ø> (ø)
server-latest	94.70% <ø> (ø)

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