Update options-state.md (#1709)

typo?

Author: Sun

src/api/options-state.md

@@ -285,7 +285,7 @@ Declare watch callbacks to be invoked on data change.
 
   The `watch` option expects an object where keys are the reactive component instance properties to watch (e.g. properties declared via `data` or `computed`) — and values are the corresponding callbacks. The callback receives the new value and the old value of the watched source.
 
-  In addition to a root-level property, The key can also be a simple dot-delimited path, e.g. `a.b.c`. Note that this usage does **not** support complex expressions - only dot-delimited paths are supported. If you need to watch complex data sources, this the imperative [`$watch()`](/api/component-instance.html#watch) API instead.
+  In addition to a root-level property, The key can also be a simple dot-delimited path, e.g. `a.b.c`. Note that this usage does **not** support complex expressions - only dot-delimited paths are supported. If you need to watch complex data sources, use the imperative [`$watch()`](/api/component-instance.html#watch) API instead.
 
   The value can also be a string of a method name (declared via `methods`), or an object that contains additional options. When using the object syntax, the callback should be declared under the `handler` field. Additional options include: