[PATCH Newlib]Add descripton for feature customizing options in newlib readme file

[Bin Cheng]

Hi,
We added several configuration options in newlib to guard code modifications
from Newlib-nano.  As a promise made before, I factored and described all
these feature customizing options in newlib/README in this patch.  Hoping
can provide a place for others to well document the options. 

Is it OK?
Thanks.
bin

2013-06-13  Bin Cheng  <bin.cheng@arm.com>
	* README: Add description for NEWLIB's feature customizing
	configuration options.
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: readme-20130608.txt
URL: <http://sourceware.org/pipermail/newlib/attachments/20130613/41d441fc/attachment.txt>