Sample app on how to write a custom RewritePolicy for Log4j 2 RewriteAppender

• Documentation on the lib website is scarce, and couldn't find any working examples, so I made this simple Hello World showing the concept
• Also, you can take a look at RewritePolicy implementations on log4j-core source jar for more information (org.apache.logging.log4j.core.appender.rewrite.PropertiesRewritePolicy.java)