DOC: Clarify float_precision behavior in read_csv and read_table docs

[sabasiddique1]

Improves the user guide documentation for the float_precision parameter used when reading CSV and other text files (e.g. read_csv, read_table).

• closes DOC: explain the float_precision parameter #64094
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.
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[jontwo]

Nice PR, thanks! Would it be possible to put example float values in too? Asking because what brought me to this parameter was some user data that was very close to 0 (with 17dp of precision). The default converter rounded it to 0, but users wanted to keep the input precision (so round-trip was the option we needed).