Fix typo: removed double 'the'

Author: FarzadMohtasham

src/part-guide/async-await.md

@@ -163,7 +163,7 @@ Here's a tiny example of running an async function on a separate task by using `
 
 Similar to the last example, we have two functions printing "hello" and "world!". But this time we run them concurrently (and in parallel) rather than sequentially. If you run the program a few times you should see the strings printing in both orders - sometimes "hello" first, sometimes "world!" first. A classic concurrent race!
 
-Let's dive into what is happening here. There are three concepts in play: futures, tasks, and threads. The `spawn` function takes a future (which remember can be made up of many smaller futures) and runs it as a new Tokio task. Tasks are the the concept which the Tokio runtime schedules and manages (not individual futures). Tokio (in its default configuration) is a multi-threaded runtime which means that when we spawn a new task, that task may be run on a different OS thread from the task it was spawned from (it may be run on the same thread, or it may start on one thread and then be moved to another later on).
+Let's dive into what is happening here. There are three concepts in play: futures, tasks, and threads. The `spawn` function takes a future (which remember can be made up of many smaller futures) and runs it as a new Tokio task. Tasks are the concept which the Tokio runtime schedules and manages (not individual futures). Tokio (in its default configuration) is a multi-threaded runtime which means that when we spawn a new task, that task may be run on a different OS thread from the task it was spawned from (it may be run on the same thread, or it may start on one thread and then be moved to another later on).
 
 So, when a future is spawned as a task it runs *concurrently* with the task it was spawned from and any other tasks. It may also run in parallel to those tasks if it is scheduled on a different thread.