doc cpu: add example output

docs/20_Checks/check_cpu.md

@@ -42,3 +42,26 @@ If there are processes with status D they will be shown (to analyze cpu waits).
     check cpu usage.
     It shows a warning if usage is higer 60%.
     It shows critical status if usage is higer 80% or io wait is 40%
+
+```txt
+./check_cpu -w 60 -c 80 -i 40
+OK: CPU-USAGE [%] 11.3 ... user: 6.2 - system: 4.1 - idle: 88.7 - wait: 0.0
+
+Limits: usage warn at 60 .. critical at 80 .. io wait limit 40
+INFO  : cpu is in normal ranges.
+
+Legend:
+
+   hwi - Time spent handling hardware interrupt routines. (Whenever a peripheral unit want attention form the CPU, it literally pulls a line, to signal the CPU to service it)
+   swi - Time spent handling software interrupt routines. (a piece of code, calls an interrupt routine...)
+    st - Time spent on involuntary waits by virtual cpu while hypervisor is servicing another processor (stolen from a virtual machine)
+
+  nice - Time spent running niced user processes (User defined priority)
+  wait - Time spent on waiting on IO peripherals (eg. disk)
+
+system - Time spent in kernel space
+  user - Time spent in user space
+  idle - Time spent in idle operations
+
+ |cpu-usage=11.3;60;80;0;100 cpu-wait=0.0;;40;0;100 cpu-system=4.1;;;0;100 cpu-user=6.2;;;0;100 cpu-idle=88.7;;;0;100 cpu-nice=0.0;;;0;100 cpu-hwi=0.5;;;0;100 cpu-swi=0.5;;;0;100 cpu-st=0.0
+```