docs(mq): fix title level (#9395)

This should be level 2 title and not under "when things change".

Author: jd

src/content/docs/merge-queue/parallel-checks.mdx

@@ -131,7 +131,7 @@ Parallel Checks adapt automatically as your code and rules evolve:
   `reset_on_external_merge` — see [Lifecycle: Base Branch
   Updates](/merge-queue/lifecycle#base-branch-updates).
 
-### Skip Intermediate Results
+## Skip Intermediate Results
 
 By default, each speculative draft that includes a pull request must pass
 before that pull request can be merged. When