Fix infra docs

Previously we had the wrong path to the recipes.py script and an incorrect argument list.

infra/README.md

@@ -30,8 +30,8 @@ by the [luci/recipes-py github project](https://github.com/luci/recipes-py).
 The typical cyle for editing a recipe is:
 
 1. Make your edits.
-2. Run `build/slave/recipes.py train simulation_test flutter` to update expected files  (remove the flutter if you need to do a global update).
-3. Run `build/slave/recipes.py run flutter/flutter` (or flutter/engine) if something was strange during training and you need to run it locally.
+2. Run `build/scripts/slave/recipes.py simulation_test train flutter` to update expected files  (remove the flutter if you need to do a global update).
+3. Run `build/scripts/slave/recipes.py run flutter/flutter` (or flutter/engine) if something was strange during training and you need to run it locally.
 4. Upload the patch (`git commit`, `git cl upload`) and send it to someone in the `recipes/flutter/OWNERS` file for review.
 
 Most of the functionality for recipes comes from recipe_modules, which are