Added note about Java 8 vendors (#11530)

* Added note about Java 8 vendors

* Update release-notes.html

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

@@ -335,7 +335,9 @@
         <h2 id="supportedversions">Supported Technologies</h2>
 
         <p>
-            Vaadin Framework 8 is compatible with <b>Java 8 and 9</b>. Vaadin Framework
+            Vaadin Framework 8 is compatible with <b>Java 8 and 9</b>. 
+	Vaadin Framework 8 is developed and tested with Oracle JDK, but other
+		compliant Java distributions should work as well. Vaadin Framework
             8 is especially supported on the following <b>operating
                 systems</b>:
         </p>