Merge #13835: [trivial,doc] Fix memory consistency model in comment

fe7180c [trivial,doc] Fix memory consistency model in comment (Jesse Cohen)

Pull request description:

  Updating a comment overlooked during review in #13247

Tree-SHA512: 0bd54ba1c265fdd77fd6e12ad0be46dd422348f7d926ce9abaca53fdb3a3c55c0d1cd90b4382321352076f4a81e2249c0014cd789f47a3637cb93bd983cb4657

Author: laanwj

src/scheduler.h

@@ -110,7 +110,7 @@ class SingleThreadedSchedulerClient {
 
     /**
      * Add a callback to be executed. Callbacks are executed serially
-     * and memory is sequentially consistent between callback executions.
+     * and memory is release-acquire consistent between callback executions.
      * Practially, this means that callbacks can behave as if they are executed
      * in order by a single thread.
      */