syncslides: fix and slightly expand project desc

(noticed when reviewing james's java->syncslides migration cl)

Change-Id: I7fa7faac669418f6f20b3e4316dbdc7a4bd8b6a4
diff --git a/README.md b/README.md
index dd58add..f5585c8 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # SyncSlides
 
-A simple multi-device presentation system built.
+A simple multi-device presentation system, with state synced across devices
+using Syncbase.
 
 ## Java/Android Version