docs: fix typo in react.md (#1421)

Author: cseas

packages/lit-dev-content/site/docs/v3/frameworks/react.md

@@ -117,7 +117,7 @@ Try it out in the [React slots playground example](/playground/#sample=examples/
 
 The `events` option takes an object that maps React prop names to event names. When a component user passes a callback prop with one of the event prop names, the wrapper will add it as an event handler for the corresponding event.
 
-While the the React prop name can be whatever you want, the recommended convention is to add `on` in front of the event name. This matches how React is planning to implement event support for custom elements. You should also make sure this prop name does not collide with any existing properties on the element.
+While the React prop name can be whatever you want, the recommended convention is to add `on` in front of the event name. This matches how React is planning to implement event support for custom elements. You should also make sure this prop name does not collide with any existing properties on the element.
 
 In TypeScript, the event type can be specified by casting the event name to the `EventName` utility type. This is a good practice to do so that React users will get the most accurate types for their event callbacks.