add --use-3dnow argument
diff --git a/README b/README
index 5f0aeb1..4b745eb 100644
--- a/README
+++ b/README
@@ -81,6 +81,12 @@
configure without --sse-os. Note that --disable-asm-optimizations
overrides --sse-os.
+--use-3dnow : If you are building for an AMD CPU which has 3DNOW!
+support, you can use this flag to enable some assembly routines
+which use 3DNOW! instructions. There have been some reports that
+they may cause flac to crash, which is why it is not turned on
+by default.
+
===========================
Building with Makefile.lite