Bump to version 0.9.0

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/README.md b/README.md
index a370b73..dcda00a 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # mcuboot
 
-This is mcuboot, version 0.9.0-rc2
+This is mcuboot, version 0.9.0
 
 ## Overview