minor update of README

Author: shiozaki

README

@@ -1,6 +1,6 @@
 This software aims to replace the predecesor SMITH ver1.0 written in python.
 
-Although it is open and world-readable, I would appreciate it if you let me know when you start tweaking the code. Note that code generation part is still missing, and therefore, it cannot be used as it is as of March 2012.
+Although it is open and world-readable, I would appreciate it if you let me know when you start tweaking the code. Note that code generation part is still missing, and therefore, it cannot be used as is as of March 2012.
 
 Contributor (as of March 2012):
   Toru Shiozaki <shiozaki@northwestern.edu>