add markdown help for snmp_printer

docs/20_Checks/check_snmp_printer.md

+## Check SNMP printer
+
+Script: `check_snmp_printer`
+
+**check_snmp_printer** is a wrapper for Nagios plugin check_snmp_printer. Its main task is to fetch SNMP authentication parameters from a config file and then call the Nagios check.
+
+## Requirements
+
+* snmpget
+* snmpwalk
+* check_snmp_printer or an update of it eg. <https://github.com/Tylan/check_snmp_printer/tree/master>
+
+## Standalone installation
+
+From this repository ypu need next to this script:
+
+* `inc_pluginfunctions` shared function for all IML checks written in bash
+* `check_snmp_includes` with a shared snmp config reader
+
+## Syntax
+
+Start the script without parameter to get the help.
+
+```txt
+______________________________________________________________________
+
+CHECK_SNMP_PRINTER
+v1.0
+
+(c) Institute for Medical Education - University of Bern
+Licence: GNU GPL 3
+
+https://os-docs.iml.unibe.ch/icinga-checks/Checks/check_snmp_printer.html
+______________________________________________________________________
+
+This is a wrapper for the check_snmp_printer plugin.
+Maybe you want to upgrade it from 
+<https://github.com/Tylan/check_snmp_printer/tree/master>
+
+The wrapper does
+
+- scan for snmp auth parameters of given host by check_snmp_includes
+- adds snmp timeout
+- executes check_snmp_printer with given other params
+
+USAGE:
+    check_snmp_printer [-d] [-c SCRIPT] -H SNMPTARGET [other params]
+
+PARAMETERS:
+
+    -d, --debug (as 1st param)
+       Debug mode: shows all generated params.
+       "-d" or "--debug" will be removed from params for 
+       check_snmp_printer script
+
+    -c SCRIPT
+       Set script to execute with full path
+       default: /usr/lib64/nagios/plugins/check_snmp_printer_v2.0.1
+
+    -H HOSTNAME
+       required: as fqdn or ip address; default: localhost
+
+    All other params for check_snmp_printer, eg.
+    --consum
+    --messages
+    --pagecount
+    --trays
+
+CONFIG FILE:
+    The config file can be multiline and has the syntax
+    [SNMPTARGET[,target2]]:[auth parameters]
+    The auth parameters set the version and all needed values to connect.
+    Snmp v2 uses a community string.
+    Snmp v3 is highly recommended (you should disable Snmp v2) and needs
+    a user and password.
+
+EXAMPLE:
+    check_snmp_printer -H 192.168.100.12 --consum
+
+```
+
+## Examples
+
+### Messages of the printer
+
+`./check_snmp_data -H 192.168.100.12 --messages`
+
+### Consumables
+
+`./check_snmp_data -H 192.168.100.12 --consum`
+
+### Number of pages printed
+
+`./check_snmp_data -H 192.168.100.12 --pagecount`
+
+### Status of trays for paper
+
+`./check_snmp_data -H 192.168.100.12 --trays`
+
+Remark: when using --trays the param `--nofeeder` will be inserted too.