Add software link

documentation/modules/exploit/linux/local/servu_ftp_server_prepareinstallation_priv_esc.md

@@ -11,6 +11,10 @@
 
 ## Vulnerable Application
 
+  [Serv-U FTP Server](https://www.serv-u.com/ftp-server-software)
+  is an FTP server for Linux and Windows; however, this module
+  targets only Linux systems.
+
   This module has been tested successfully on:
 
   * Serv-U FTP Server version 15.1.6 (x64) on Debian 9.6 (x64)
@@ -31,7 +35,7 @@
 
   **SERVU_PATH**
 
-  Path to Serv-U executable (default: `/usr/local/Serv-U/Serv-U`)
+  Path to `Serv-U` executable (default: `/usr/local/Serv-U/Serv-U`)
 
   **WritableDir**