docs: contain horizontal overflow in C API descriptions

docs: contain horizontal overflow in C API descriptions

Some documentation pages contain long C API signatures that can exceed
the content width and cause page-wide horizontal scroll overflow.

Apply contained horizontal scrolling to C API description blocks and
keep their signature rows on one line. This preserves signature
formatting while preventing them from breaking page layout.

Contained horizontal scrolling is preferred over wrapping here because
code fidelity is the priority. These blocks are intended to remain
representative of the code itself. Wrapping distorts spacing and line
structure, which affects fidelity, creates misleading renderings, and
reduces readability.

Examples:
  https://docs.kernel.org/6.15/driver-api/regulator.html
  https://docs.kernel.org/6.15/userspace-api/fwctl/fwctl-cxl.html

Signed-off-by: Rito Rhymes <rito@ritovision.com>
Assisted-by: Codex:GPT-5.4
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260323153342.33447-1-rito@ritovision.com>