docs(AstrodynamicalSolvers): add usage examples

[cadojo]

Changes

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Reviewer: @cadojo

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.43%. Comparing base (6499915) to head (a516d84).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #266   +/-   ##
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  Coverage   56.43%   56.43%           
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  Files          13       13           
  Lines        1212     1212           
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  Hits          684      684           
  Misses        528      528           

Flag	Coverage Δ
AstrodynamicalModels.jl	67.97% <ø> (ø)

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