[3.12] Docs: Fix Sphinx warnings in io.rst (GH-107903) (#108093)

Docs: Fix Sphinx warnings in io.rst (GH-107903)

- Mark up parameter and argument names properly
- If possible, link to docs for methods like `seek`, `tell`, `write`, `read`, etc.

(cherry picked from commit 5c76899dadf3bdcfdedf6f30b3ab9742cb87af04)

Co-authored-by: Erlend E. Aasland <erlend@python.org>
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: T. Wouters <thomas@python.org>