fix message

Author: brakkioris

check-plugins/dir-size/dir-size

@@ -245,7 +245,9 @@ def main():
         state = lib.base.get_worst(state, table_data[i]['state'])
 
     # build the message
-    msg += f'{len(table_data)} {lib.txt.pluralize("file", len(table_data))} checked. '
+    msg += (
+        f'{len(table_data)} {lib.txt.pluralize("directory", len(table_data))} checked. '
+    )
     if state == STATE_OK:
         msg += (
             f'{lib.txt.pluralize("", len(table_data), "It is,All are")}'