check nginx.pm version

docs/GNUmakefile

diff --git a/docs/GNUmakefile b/docs/GNUmakefile
index 7f2d45a..1198e42 100644
--- a/docs/GNUmakefile
+++ b/docs/GNUmakefile
@@ -1,6 +1,6 @@
 
-VER=	$(shell grep NGINX_VER src/core/nginx.h				\
-		| sed -e 's%^.*\"nginx/\(.*\)\"%\1%')
+VER=	$(shell grep 'define NGINX_VERSION' src/core/nginx.h		\
+		| sed -e 's/^.*\"\(.*\)\"/\1/')
 NGINX=	nginx-$(VER)
 TEMP=	tmp
 CP=	$(HOME)/java