DOC: Improve documentation for mode parameter in to_csv() method

[kevinxperese]

Pandas version checks

• I have checked that the issue still exists on the latest versions of the docs on main here

Location of the documentation

https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.to_csv.html

Documentation problem

The description for the mode parameter is too sparse. Additional information on other acceptable values would be helpful, especially mode='a'.

Suggested fix for documentation

Proposed change:
mode : str, default 'w'
String character(s) to indicate the mode in which the file is opened for writing. Valid values include: 'w' for "write" access, 'w+' or 'r+' for read and write access, 'x' or 'x+' for exclusive creation access, and 'a' or 'a+' for append access. All strings have an implied 't' for text access; binary access is not permitted.

[MaruthiKo]

Hi, I am new to Open source and I am looking forward to working on this issue, this would be my first open-source contribution.
Can you please tell me how I can help in this issue

[mroeschke]

I think linking to Python's open docstring which describes the standard mode options that pandas dispatches to would be best: https://docs.python.org/3/library/functions.html#open

[MaruthiKo]

I think linking to Python's open docstring which describes the standard mode options that pandas dispatches to would be best: https://docs.python.org/3/library/functions.html#open

I guess you are right will do that.

[kevinxperese]

I think linking to Python's open docstring which describes the standard mode options that pandas dispatches to would be best: https://docs.python.org/3/library/functions.html#open

That crossed my mind, but I haven't seen such links in documentation elsewhere, so I wasn't sure if that would be a non-standard practice.

Also, adding just a link would not solve the problem of someone coming to the page looking for the appropriate parameter to use to append content to a file. (Searching the page for the word "append" will still turn up nothing; this is what I did when I was looking for the parameter to use.)

[MaruthiKo]

I think linking to Python's open docstring which describes the standard mode options that pandas dispatches to would be best: https://docs.python.org/3/library/functions.html#open

That crossed my mind, but I haven't seen such links in documentation elsewhere, so I wasn't sure if that would be a non-standard practice.

Also, adding just a link would not solve the problem of someone coming to the page looking for the appropriate parameter to use to append content to a file. (Searching the page for the word "append" will still turn up nothing; this is what I did when I was looking for the parameter to use.)

If you don't mind me asking?
Are the changes that I made as per your suggestions good enough or should I change anything?