Fix typo in Elasticsearch help

This commit fixes a small typo in the help output displayed by
Elasticsearch when the --help flag is passed.

core/src/main/java/org/elasticsearch/bootstrap/Elasticsearch.java

@@ -62,7 +62,7 @@ class Elasticsearch extends EnvironmentAwareCommand {
             .withRequiredArg()
             .withValuesConvertedBy(new PathConverter());
         quietOption = parser.acceptsAll(Arrays.asList("q", "quiet"),
-            "Turns off standard ouput/error streams logging in console")
+            "Turns off standard output/error streams logging in console")
             .availableUnless(versionOption)
             .availableUnless(daemonizeOption);
     }