docs: automarkup.py: Skip common English words as C identifiers

docs: automarkup.py: Skip common English words as C identifiers

The automarkup extension incorrectly recognizes common English words
as C identifiers when they follow struct/union/enum/typedef keywords,
causing normal text like "... (a simple) struct that" (in `workqueue.rst`)
to be rendered as code blocks.

This patch adds Skipidentifiers list to filter out these words.

Signed-off-by: Yulong Han <wheatfox17@icloud.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260125124450.2005006-1-wheatfox17@icloud.com>