Explain count-fail-ratio in README as well

README.md

@@ -43,6 +43,30 @@ timeout per execution:
 retry -- timeout 10 $cmd
 ```
 
+### count-fail-ratio - simple statistics about retries
+
+Another tool provided is "count-fail-ratio" which can count fails, the fail
+ratio, the failure probability and timing information from repeated command
+calls. Simply call
+
+```
+count-fail-ratio $cmd
+```
+
+to execute `$cmd` automatically multiple times collecting the mentioned
+statistics.
+
+Further options to count-fail-ratio can be specified by runtime variables. For
+example to change the number of runs from the default of 20 set the variable
+"runs" while disabling computing timing information:
+
+```
+runs=100 timing=0 count-fail-ratio $cmd
+```
+
+For the complete list of variables take a look into the script file
+count-fail-ratio itself.
+
 ## Contribute
 
 This project lives in https://github.com/okurz/retry