Remove extra whitespace after P-4032.

Initial version of evbmips kernel configuration files documentation.
The goal is to give a better understanding which hardware they represent
and how to build them. Also not to lose this information over the years.

Loosely based on a README.evbarm, however has additional notes on building
targets. The file is not final, some discussion came up about the need of
*32 kernel configs. simon is planning to review.