read_fwf docs
- [X] Enhances #16950
- [X] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [X] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

Enhanced documentation on `read_fwf`: clarifies whitespace is stripped by default and how to override via setting `delimiter`.

`pandas/io/parsers/readers.py` had no mention of delimiter option.
This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks for the pull request, but it appears to have gone stale. Additionally if a fix is required it should probably be discussed in an issue before moving forward to closing in favor of a future issue