Documentation: driver-api: pps: Update PPS generator documentation

PPS documentation has a generalized section for generators. Update the
section so any new generator documentation can be appended.

Signed-off-by: Pandith N <pandith.n@intel.com>
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231016101953.27308-1-lakshmi.sowjanya.d@intel.com

Author: pandithn

Documentation/driver-api/pps.rst

@@ -200,11 +200,17 @@ Generators
 
 Sometimes one needs to be able not only to catch PPS signals but to produce
 them also. For example, running a distributed simulation, which requires
-computers' clock to be synchronized very tightly. One way to do this is to
-invent some complicated hardware solutions but it may be neither necessary
-nor affordable. The cheap way is to load a PPS generator on one of the
-computers (master) and PPS clients on others (slaves), and use very simple
-cables to deliver signals using parallel ports, for example.
+computers' clock to be synchronized very tightly.
+
+
+Parallel port generator
+------------------------
+
+One way to do this is to invent some complicated hardware solutions but it
+may be neither necessary nor affordable. The cheap way is to load a PPS
+generator on one of the computers (master) and PPS clients on others
+(slaves), and use very simple cables to deliver signals using parallel
+ports, for example.
 
 Parallel port cable pinout::