Update readme temporarily

- advisory of non-compliance with current documentation

README.md

 # Arduino driver for nRF24L01 2.4GHz Wireless Transceiver
 
+Note: March 2014, this fork was just published and is still undergoing fine tuning.
+The attached documentation is close but does NOT match the library.
+See http://TMRh20.blogspot.com for usage information and updates. 
+This readme will be updated once more is finalized.
+
 Design Goals: This library is designed to be...
 
 * Maximally compliant with the intended operation of the chip
+* As efficient in operation as possible
 * Easy for beginners to use
 * Consumed with a public interface that's similiar to other Arduino standard libraries
 * Built against the standard SPI library.