added bison/yacc static build dependency

README.md

@@ -51,7 +51,7 @@ Parts of the project are originally copyright (c) 2012-2013 The Cryptonote devel
 ### On Unix and Linux:
 
 Dependencies: GCC 4.7.3 or later, CMake 2.8.6 or later, libunbound 1.4.16 or later (note: Unbound is not a dependency, libunbound is), and Boost 1.53 or later (except 1.54, [more details here](http://goo.gl/RrCFmA)).
-Static Build Additional Dependencies: ldns 1.6.17 or later, expat 1.1 or later
+Static Build Additional Dependencies: ldns 1.6.17 or later, expat 1.1 or later, bison or yacc
 
 **Basic Process:**