update docs

docs/30_Scripts.md

@@ -139,6 +139,7 @@ The inc_config.sh mus contain 3 variables for pruning
     prune_basedir=/netshare/restic-backup
     prune_params="--group-by paths,tags --prune --keep-within 180d --max-unused unlimited --max-repack-size 100M --cleanup-cache"
     prune_skipdays="7"
+    prune_cachedir=${prune_basedir}/.cache_for_pruning
 ```
 
 ## rest_pruner.cfg