Add note that JDK8 is required to build and to run the server

README.md

@@ -7,7 +7,7 @@ Keycloak is an SSO Service for web apps and REST services. For more information
 Building
 --------
 
-Ensure you have JDK 7 (or newer), Maven 3.2.1 (or newer) and Git installed
+Ensure you have JDK 8 (or newer), Maven 3.2.1 (or newer) and Git installed
 
     java -version
     mvn -version

docbook/auth-server-docs/reference/en/en-US/modules/server-installation.xml

@@ -4,7 +4,8 @@
     <section>
         <title>Installation</title>
         <para>
-            Keycloak Server has three downloadable distributions.
+            Keycloak Server has three downloadable distributions. To run the Keycloak server you need to have Java 8 already
+            installed.
         </para>
         <para>
             <itemizedlist>