Use triple backtickes instead of pre

Author: Petros Amiridis

en/eBook/12.3.md

@@ -40,7 +40,7 @@ But we can see some implementations daemon many online methods, such as the foll
 
 - Another solution is to use the syscall, but this solution is not perfect:
 
-<pre>
+```
 	package main
 	 
 	import (
@@ -109,7 +109,7 @@ But we can see some implementations daemon many online methods, such as the foll
 	 
 		return 0
 	}
-</pre>
+```
 
 The above proposed two implementations Go's daemon program, but I still do not recommend you to realize this, because the official announcement has not officially support daemon, of course, the first option is more feasible for now, but it is currently open source library skynet in adopting this program do daemon.