Updated read_excel docstring to match style guide formatting
Fixes `read_excel()` docstring to match docstring formatting style guide:
- Issue: https://github.com/pandas-dev/pandas/issues/53674. 
- Style Guide: https://pandas.pydata.org/docs/development/contributing_docstring.html

Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.