Update, fix and describe manual files
    
    man files are still missing in source files.
    
    Issue tracking current status:
    https://github.com/sysown/proxysql/issues/3564
    
    Original author of content of that file: René Cannaò
    
    * Path file in installation process for man files has been fixed.
    * man file has been updated for v2.2.0 of proxysql.
    * Description for Source2 file (manual) has been added to spec file.
    * Added author of modification next to credentials.