README.md: require JDK8.

Should be in 47f3ed8 commit.

[ci skip]

Author: php-coder

README.md

@@ -23,7 +23,7 @@ Site is under development and doesn't exist on the Internet so unfortunately you
 
 If you are programmer/sysadmin or you just feeling that you are able to run local version of the site then follow the following instructions:
 
-* install Java (at least 7th version is required)
+* install Java (at least 8th version is required)
 * install Maven
 * clone this project
 * from the console inside the directory with source code, execute command `mvn clean jetty:run`