Thermometer documentation typo

Author: chrisseaton

tools/docs/Thermometer-Manual.md

@@ -79,8 +79,8 @@ You'll see log lines like this:
 
 ## Monitoring performance
 
-`--thermometer.IPS=test.rb:24` will install an iterations-per-second counter
-on any statements at this location. You should ensure there is just one
+`--thermometer.IterationPoint=test.rb:24` will install an iterations-per-second
+counter on any statements at this location. You should ensure there is just one
 statement at this location as each statement run will count as an iteration.
 
 ```