doc: build requires GNU make 3.81+

diff --git a/README.md b/README.md
index 39e8332..309d539 100644 (file)
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@ Evented I/O for V8 javascript. [![Build Status](https://secure.travis-ci.org/joy
 
 ### To build:
 
-Unix/Macintosh (requires python 2.6 or 2.7):
+Unix/Macintosh. Requires python 2.6 or 2.7 and GNU make 3.81 or newer:
 
     ./configure
     make