Fix wording in documentation

Author: vitusortner

kotlinx-coroutines-core/common/src/Job.kt

@@ -582,7 +582,7 @@ public fun CoroutineContext.cancel(cause: Throwable? = null): Boolean =
     (this[Job] as? JobSupport)?.cancelInternal(cause) ?: false
 
 /**
- * Cancels all children of the [Job] in this context, without touching the the state of this job itself
+ * Cancels all children of the [Job] in this context, without touching the state of this job itself
  * with an optional cancellation cause. See [Job.cancel].
  * It does not do anything if there is no job in the context or it has no children.
  */