Add windows build docs to extra dist files.

Makefile.am

@@ -9,7 +9,7 @@ endif
 
 EXTRA_DIST	= example.conf m4/gnulib-cache.m4 linux-usb-cgminer \
 		  ADL_SDK/readme.txt api-example.php miner.php	\
-		  API.class API.java api-example.c
+		  API.class API.java api-example.c windows-build.txt
 
 SUBDIRS		= lib compat ccan