Add a mention of support for v-bind.sync (#1459)

* Add a mention of support for v-bind.sync

* Remove unnecessary quotes from v-bind example

Author: davidkhess

src/v2/guide/components.md

@@ -627,6 +627,14 @@ For the child component to update `foo`'s value, it needs to explicitly emit an
 this.$emit('update:foo', newValue)
 ```
 
+The `.sync` modifier can also be used with `v-bind` when using an object to set multiple properties at once:
+
+```html
+<comp v-bind.sync="{ foo: 1, bar: 2 }"></comp>
+```
+
+This has the effect of adding `v-on` update listeners for both `foo` and `bar`.
+
 ### Form Input Components using Custom Events
 
 Custom events can also be used to create custom inputs that work with `v-model`. Remember: