docs($timeout): reword sentence for clarity

Closes #13302

Author: etsuo

src/ng/timeout.js

@@ -33,8 +33,8 @@ function $TimeoutProvider() {
       * @param {boolean=} [invokeApply=true] If set to `false` skips model dirty checking, otherwise
       *   will invoke `fn` within the {@link ng.$rootScope.Scope#$apply $apply} block.
       * @param {...*=} Pass additional parameters to the executed function.
-      * @returns {Promise} Promise that will be resolved when the timeout is reached. The value this
-      *   promise will be resolved with is the return value of the `fn` function.
+      * @returns {Promise} Promise that will be resolved when the timeout is reached. The promise
+      *   will be resolved with the return value of the `fn` function.
       *
       */
     function timeout(fn, delay, invokeApply) {