Update html.parser.rst (GH-30678)

Update html.parser.rst (GH-30678)

This PR for the documentation of the [html.parser](https://docs.python.org/3/library/html.parser.html) module will

- fix a terminology mistake (‘start of a tag’ -> ‘start tag of an element’);
- mention the parameter names of the `HTMLParser.handle_*` methods where missing.
(cherry picked from commit 2945f5a7c51200bfc5c493ccb626fc414e1385b1)

Co-authored-by: Géry Ogam <gery.ogam@gmail.com>