Documentation: e100: Update the Intel 10/100 driver doc

Over the years, several of the links have changed or are no longer valid
so update them.  In addition, the default values were incorrect for a
couple of parameters.

Converted the text file to the reStructuredText (RST) format, since the
Linux kernel documentation now uses this format for documentation.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>