[MINOR][DOCS] Fix typos at ExecutorAllocationManager.scala
### What changes were proposed in this pull request?
This PR fixes some typos in <code>core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala</code> file.
### Why are the changes needed?
<code>spark.dynamicAllocation.sustainedSchedulerBacklogTimeout</code> (N) is used only after the <code>spark.dynamicAllocation.schedulerBacklogTimeout</code> (M) is exceeded.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
No test needed.
Closes #29351 from JoeyValentine/master.
Authored-by: JoeyValentine <rlaalsdn0506@naver.com>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
diff --git a/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala b/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
index 85409d5..1570f86 100644
--- a/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
+++ b/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
@@ -47,8 +47,8 @@
* executors that could run all current running and pending tasks at once.
*
* Increasing the target number of executors happens in response to backlogged tasks waiting to be
- * scheduled. If the scheduler queue is not drained in N seconds, then new executors are added. If
- * the queue persists for another M seconds, then more executors are added and so on. The number
+ * scheduled. If the scheduler queue is not drained in M seconds, then new executors are added. If
+ * the queue persists for another N seconds, then more executors are added and so on. The number
* added in each round increases exponentially from the previous round until an upper bound has been
* reached. The upper bound is based both on a configured property and on the current number of
* running and pending tasks, as described above.
