contrib: Set check-params-in-docs.py to skip tables of values of a param

Currently check-params-in-docs.py reports extra params being listed in
invoke.texi.  However, those aren't actual params but items in a table of
possible values of the aarch64-autove-preference param.

This patch changes check-params-in-docs.py to ignore similar tables.

contrib/ChangeLog:

	* check-params-in-docs.py: Skip tables of values of a param.
	Remove code that skips items beginning with a number.

Signed-off-by: Filip Kastl <fkastl@suse.cz>