Improve fname documentation for to_parquet

[larroy]

Code Sample, a copy-pastable example if possible

Should to_parquet without file behave the same way than to_json in which if no file is specified we return the buffer?

[TomAugspurger]

Probably not, since parquet isn't a plaintext format.

[WillAyd]

Think I am agreed with Tom. Having all to_* functions return the same thing is also a non-goal, as it just doesn't make sense in all cases (to_sql comes to mind)

[larroy]

Thanks for your answers.
It would still be useful to get the buffer without having to pass through the filesystem. Would a contribution in this direction be accepted? (At least for the functions that might make sense, ie. not for to_sql...)

[WillAyd]

The documentation can be improved but you can pass an io.BytesIO object if you don't want to write to disk. I think path-like objects work as well - any interest in updating the docs?

[larroy]

Sure, I would be happy to update them. I will link the PRs here. Thank you.

[alimcmaster1]

@larroy you still interested in working on this?

[larroy]

Sorry was caught up with other things, let me have a look at this this week.