DOC: Fix read_hdf docstring
Read HDF docstring was not in NumPy format.  Corrects the formatting

[skip ci]

- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`


The rendered docstring

https://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_hdf.html

does not have the correct appearance. can you run the validation script on this? Seems inevitable since signature uses **kwargs to capture most inputs.

```
Errors found:
        Errors in parameters section
                Unknown parameters {'iterator', 'start', 'chunksize', 'where', 'columns', 'stop '}
``` CI wasn't running, pushed a commit w/ a few small changes (mentioning `__fspath__`) to re-trigger it. Merging since the doc build passed cleanly.