Update instructions to recommend use of included incore script.

README.FIPS

 Preliminary status and build information for FIPS module v2.0
 
-NB: if you are cross compiling you now need to use the latest "incore2" script
-from http://www.openssl.org/docs/fips/incore2
+NB: if you are cross compiling you now need to use the latest "incore" script
+this can be found under the util/ in the tarballs.
 
 If you have any object files from a previous build do: