Fixed reference for README as markdown file

Makefile

@@ -7,7 +7,7 @@ dataroot = $(prefix)/share
 datadir = $(dataroot)/graudit
 bindir = $(prefix)/bin
 SIGNATURES := signatures/default.db signatures/php.db  signatures/perl.db signatures/python.db signatures/asp.db signatures/java.db signatures/strings.db signatures/c.db signatures/dotnet.db signatures/ruby.db signatures/actionscript.db signatures/ios.db signatures/android.db signatures/all.db
-DISTFILES := Changelog  graudit  LICENSE  README graudit.1
+DISTFILES := Changelog  graudit  LICENSE  README.md graudit.1
 VERSION=`./graudit -v | cut -d' ' -f 3`
 .PHONY : clean install uninstall userinstall test signatures