Update readme

README.md

@@ -141,6 +141,28 @@ parameter set to `true`:
    }
    ```
 
+## Synchronized map
+
+A map that will auto save it's values to the database. Useful for values that
+mostly get updated, like settings
+
+   ```dart
+   import 'package:observable/observable.dart';
+   import 'package:sqlcool/sqlcool.dart';
+
+   // Define the map with initial data
+   var myMap = SynchronizedMap(
+      db: db, // an Sqlcool database
+      table: "a_table",
+      where: "id=1",
+      data: ObservableMap.from({"k": "v"}),
+      verbose: true
+   );
+
+   // Changing the map will auto update the data in the database:
+   myMap.data["k"] = "v2";
+   ```
+
 ## Todo
 
 - [x] Upsert