Add checks for super user exists

ReadMe.md

@@ -21,11 +21,13 @@ Two files must be created
 
 Example file is `pgbackrest.sample.cfg`
 
-This file holds the sudo_user for calling the commands
+This file holds the sudo_user for calling the commands and the main pgbackrest config file.
+If the super user or config file does not exists an error will be shown
 
 ```ini
 [PgBackRest]
 sudo_user=postgres
+pgbackrest_config=/etc/pgbackrest.conf
 ```
 
 ### `config/stanza.cfg`
@@ -44,7 +46,14 @@ The forth optional parameter is the super user to use
 
 If parameters are not used but laters are, the empties need to be set with just the ":"
 
-`stanza::/conifg`
+`stanza::/config`
+
+The script checks for the following things during each run
+
+- stanza name exists in the main config file, or in the override config file if set
+- check if repo number exist in main config file, or in the override config file if set
+- override config file exists
+- override super does not exist
 
 ```ini
 [stanzas]