docs(fix incorrect info)

Closes #58.

README.md

@@ -192,12 +192,12 @@ Spruce.store('form', {
     email: 'support@ryangjchandler.co.uk'
 })
 
-Spruce.watch('form.email', (old, next) => {
-    // do something with the values here
+Spruce.watch('form.email', value => {
+    // do something with the new value here
 })
 ```
 
-In the above snippet, when we change the value of `form.email` either from a component or externally in a separate JavaScript file, our callback will be invoked and will receive the old value, as well as the new value. This can be useful for running automatic inline validation when a property changes, or triggering an action elsewhere in another component without the need for dispatching events.
+In the above snippet, when we change the value of `form.email` either from a component or externally in a separate JavaScript file, our callback will be invoked and will receive the new value. This can be useful for running automatic inline validation when a property changes, or triggering an action elsewhere in another component without the need for dispatching events.
 
 > **Note**: you can get stuck in an watch loop if you're updating other store properties that also have watchers defined.