Allow setting of pgbackrest config file for each stanza

ReadMe.md

@@ -34,11 +34,16 @@ Example file is `stanza.sample.cfg`
 
 This files holds the stanzas to backup
 
+`stanza:repo number:path to config file`
+
 If the stanza has several repo settings as in "repo1-...", "repo2-..." then the repo to target can be listed in here by ":repo number"
 
+The third optional parameter is a config file path
+
 ```ini
 [stanzas]
 stanza_a
 stanza_b:1
 stanza_b:2
+stanza_c::/etc/to/config
 ```