Add `PyObject` type conversion note

[banchan86]

Motivation

This is the second roadblock that people have encountered. Problems with type conversion aren't unique to this package (see bonsai-rx/docs#34). However for this package it is critically important for using the output of the Get operator and the PyObject type is pretty obscure.

• https://github.com/orgs/bonsai-rx/discussions/2040
• https://github.com/orgs/bonsai-rx/discussions/2005

Proposed solution

@ncguilbeault has again written a nice answer in the comments section of the above discussions, and the solution is short enough that it could be incorporated as a note into the Introduction article where Get is mentioned as well as in the API reference.

Alternative solutions

• Packaging the ConvertPythonObjectToCSharp extension from Bonsai.ML.Python as a new operator for this package
  • Note: There may be other extensions in there that could also be helpful for other common issues?
• Linking to a general type conversion article once it is created Type conversion article docs#34