Adding example schema validation and example on how to use ORM

[dr-rodriguez]

Adding example schema validation and example on how to use ORM in basic ingests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6b9530d) 94.74% compared to head (46ff133) 94.84%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #67      +/-   ##
==========================================
+ Coverage   94.74%   94.84%   +0.09%     
==========================================
  Files           6        6              
  Lines         590      601      +11     
==========================================
+ Hits          559      570      +11     
  Misses         31       31              

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[dr-rodriguez]

There was a lot of Black formatting changes on schema_example.py, but the core part of it is the addition of validates in the Sources definition.

[dr-rodriguez]

Before diving into specific use cases in SIMPLE or Astrodb-template, I wanted to make sure astrodbkit2's documentation and testing was updated to demonstrate how validation could work.