update Java version to 17

Author: vladak

index.html

@@ -58,7 +58,7 @@ <h2>{OpenGrok</h2>
 
         <ul>
             <li>
-                <a href="http://www.oracle.com/technetwork/java/">Java</a> 11 or later
+                <a href="http://www.oracle.com/technetwork/java/">Java</a> 17 or later
             </li>
 
             <li>