Copy description from Cargo.toml to METADATA

Test: make
Change-Id: Ib5cc1cf092054982eaf7d32ebda62f5a8da6f7d2
diff --git a/METADATA b/METADATA
index 752f631..b8b9d82 100644
--- a/METADATA
+++ b/METADATA
@@ -1,5 +1,5 @@
 name: "codespan-reporting"
-description: "Beautiful diagnostic reporting for text-based programming languages."
+description: "Beautiful diagnostic reporting for text-based programming languages"
 third_party {
   url {
     type: HOMEPAGE