Update release notes to mention correct Java versions (#10576)

all/src/main/templates/release-notes.html

@@ -333,7 +333,7 @@
         <h2 id="supportedversions">Supported Technologies</h2>
 
         <p>
-            Vaadin Framework 8 is compatible with <b>Java 8</b> and newer. Vaadin Framework
+            Vaadin Framework 8 is compatible with <b>Java 8 and 9</b>. Vaadin Framework
             8 is especially supported on the following <b>operating
                 systems</b>:
         </p>