Document Python feature support bug

[dsfaccini]

Found these while testing pydantic-ai's CodeModeToolset

Blocked features (need tests to document)

• While loops (this one you may have already fixed today morning if I understood correctly)
• datetime (not sure if we wanna support this one but it's arguably as useful if not more than math)
• Slice syntax: items[:3], text[0:2] (trace)
• Continue/break statements (trace)
• Await expressions

[samuelcolvin]

@dsfaccini please can you check everything except datetime is working for you.