Add change to readme

Author: mrudzki

README.md

@@ -97,6 +97,7 @@ Options:
     -v, --verbose                    More output
         --fail-fast=[N]
         --seed SEED                  Seed for rspec
+        --print_failed_group             Prints group that had failures in it
 ```
 
 ## Development

lib/turbo_tests/cli.rb

@@ -83,7 +83,7 @@ def run
           seed = s
         end
 
-        opts.on("--print_failed_group") do
+        opts.on("--print_failed_group", "Prints group that had failures in it") do
           print_failed_group = true
         end
       }.parse!(@argv)