Update to Python node editor documentation

[hwahlstrom]

Purpose

Updating Python node editor documentation for https://jira.autodesk.com/browse/DYN-5727
This update includes content revisions and formatting changes.

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated

Release Notes

Updated Python node documentation regarding the Python 2 to 3 conversion. The content was refreshed and formatting improved for easier legibility.

Reviewers

@QilongTang @Amoursol

[Amoursol]

@hwahlstrom content looks good to me! But something funky is going on with a bunch of other files, @QilongTang may be able to shed more light here.

[QilongTang]

@hwahlstrom content looks good to me! But something funky is going on with a bunch of other files, @QilongTang may be able to shed more light here.

Hi Sol, that is one of the Github beta feature to show warnings on project files Github could report. Please ignore

[QilongTang]

Sporadic failure reported DynamoCoreWpfTests.CoreUserInterfaceTests.WorkspaceContextMenu_TestIfOpenOnRightClick Merging