YARN-8070. Yarn Service API site doc broken due to unwanted character in YarnServiceAPI.md (Gour Saha via wangda)

Change-Id: I22428b2f128d16e79ebbdeaf32869566963d0c6f
(cherry picked from commit 24f75e097a67ae90d2ff382bb2f2559caa02f32f)
(cherry picked from commit c98dd3bf18f6551f5be912ed36264a21cf8d42d9)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/yarn-service/YarnServiceAPI.md

@@ -1,4 +1,4 @@
-# <!---
+<!---
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at