Update Inspector API doc to show an example of printing data

[GregoryComer]

📚 The doc issue

We link to our existing Inspector APIs page in a number of locations. The user will go to this to understand how to read an etdump. The info is there, but it would be nice to have a clear example of Python code and output at the top of the page. That way, users will see what they should use in the common case, rather than needing to read through the full API surface.

Suggest a potential alternative/fix

Update

executorch/docs/source/model-inspector.rst

Line 4 in 851cffb

Overview

to include a simple example at the top of the page. It should give the python commands to import the inspector, load a file, and call print_data_tabular(). Include truncated output for a simple model.

cc @mergennachin @AlannaBurke