Update README.md

Include more completely instructions on how to build with autotools.

Author: alanxz

README.md

@@ -92,6 +92,7 @@ utilities you need are autoconf v2.59+, automake v1.9+, libtool v2.2+, and pkg-c
 
 Then the standard autotools build procedure will build rabbitmq-c:
 
+ autoreconf -i
  ./configure
  make
  make install