Wrap description to stay under 80 chars. (#15)

pubspec.yaml

diff --git a/pubspec.yaml b/pubspec.yaml
index 5be68b0..b058fbe 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,7 +1,8 @@
 name: http_multi_server
 version: 2.0.7-dev
 
-description: A dart:io HttpServer wrapper that handles requests from multiple servers.
+description: >-
+  A dart:io HttpServer wrapper that handles requests from multiple servers.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/dart-lang/http_multi_server