ceph io: fix output of help text

docs/20_Checks/check_ceph_io.md

@@ -18,35 +18,40 @@ icingaclient ALL=(ALL) NOPASSWD: /bin/ceph
 ```txt
 ______________________________________________________________________
 
-CHECK_CEPH_OSD
-v1.7
+CHECK_DISK-IO
+v1.1
 
 (c) Institute for Medical Education - University of Bern
 Licence: GNU GPL 3
 
-https://os-docs.iml.unibe.ch/icinga-checks/Checks/check_ceph_osd.html
+https://os-docs.iml.unibe.ch/icinga-checks/Checks/check_disk-io.html
 ______________________________________________________________________
 
-Show cheph osd status: how many OSDs exist and how many are up/ down.
-This check sends performance data.
+Disk infos based on /sys/block/[NAME]/stat
+See https://www.kernel.org/doc/Documentation/block/stat.txt
+and https://www.kernel.org/doc/Documentation/iostats.txt
 
-On your cluster you might want to increase the values for warning and
-critical level.
+The system data are counters that are difficult to read.
+The output of this check for each value a delta value per second since 
+last check.
 
 SYNTAX:
-check_ceph_osd [-w WARN_LIMIT] [-c CRITICAL_LIMIT]
+check_disk-io -m MODE
 
 OPTIONS:
+
+    -m MODE        set mode for type of output (required)
     -h or --help   show this help.
-    -w VALUE       warning level  (default: 1)
-    -c VALUE       critical level (default: 2)
 
-EXAMPLE:
-check_ceph_osd
-    no parameters; normal usage to get the ceph osd status
+PARAMETERS:
 
-check_ceph_osd -c 10
-    change to critical level if 10 osds are down.
+    MODE
+        io         read I/Os, write I/Os, discard I/0s
+        ticks      read ticks, write ticks, discard ticks
+        wait       total wait time for all requests
+
+EXAMPLE:
+check_disk-io -m io
 
 ```