updated changelog for JENKINS-19091

changelog.html

@@ -60,6 +60,10 @@ Upcoming changes</a>
   <li class=bug>
     Form validation methods weren't getting triggered when one of its dependency controls change.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19124">issue 19124</a>)
+  <li class=bug>
+    Correct help text of Label field in automatic installation of tools in global configuration.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19091">issue 19091</a>)
+  
 </ul>
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