drm/xe/configfs: Minor fixes to documentation

Add a few missing punctuation and line breaks and make the syntax for
code snippets common to all of them.

Reviewed-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Link: https://lore.kernel.org/r/20250821-psmi-v5-11-34ab7550d3d8@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>