Documentation: hid: intel-ish-hid: remove section numbering

Remove section numbering from the Intel Integrated Sensor Hub (ISH)
documentation to simplify the structure, making it easier to maintain
and update in the future.

Suggested-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Qianru Huang <qianru.huang@intel.com>
Signed-off-by: Zhang Lixu <lixu.zhang@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>