6468 docs and harmonize

docs/20_Checks/check_ceph_io.md

@@ -9,6 +9,10 @@ It returns a single line for the status and performance data.
 
 * `ceph` binary and sudo permission on it to get the information
 
+```txt
+icingaclient ALL=(ALL) NOPASSWD: /bin/ceph
+```
+
 ## Syntax
 
 ```txt