YARN-6338. Typos in Docker docs: contains => containers. (Contributed by Zoltan Siegl)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/DockerContainers.md

@@ -179,7 +179,7 @@ The following properties should be set in yarn-site.xml:
     <value></value>
     <description>
       Optional. A comma-separated list of users who are allowed to request
-      privileged contains if privileged containers are allowed.
+      privileged containers if privileged containers are allowed.
     </description>
   </property>