pkg/watcher: update REAME descriptions

TBR

Review URL: https://codereview.chromium.org//439713007

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/watcher@38863 260f80e4-7a28-3924-810f-c04153c831b5

pkgs/watcher/README.md

diff --git a/pkgs/watcher/README.md b/pkgs/watcher/README.md
index 75b0470..61cc1f9 100644
--- a/pkgs/watcher/README.md
+++ b/pkgs/watcher/README.md
@@ -1,2 +1,4 @@
-A file watcher. It monitors (currently by polling) for changes to contents of
-directories and notifies you when files have been added, removed, or modified.
\ No newline at end of file
+A file system watcher.
+
+It monitors changes to contents of directories and sends notifications when
+files have been added, removed, or modified.