DOC: Input/Output page contains only input functions

[attack68]

Location of the documentation

https://pandas.pydata.org/pandas-docs/dev/reference/io.html#html

Documentation problem

The title is Input/Output but all linked methods are read_xyz(), and there is little if any reference to any write_xyz() or `to_xyzz methods.

Suggested fix for documentation

Perform a review and enure all input/output methods are referenced on the page.

[gansel51]

See linked PR @attack68