Copy description from Cargo.toml to METADATA

Test: make
Change-Id: Ibc3bb790788314501475c42b75f7033f03d85aa8
diff --git a/METADATA b/METADATA
index fadefbd..2f3c213 100644
--- a/METADATA
+++ b/METADATA
@@ -1,5 +1,5 @@
 name: "bitflags"
-description: "A Rust macro to generate structures which behave like a set of bitflags."
+description: "A macro to generate structures which behave like bitflags."
 third_party {
   url {
     type: HOMEPAGE