Add example for filtering recipes when using test train

When updating only a single recipe, filtering out that recipe
is a lot faster than running all recipes at the same time.
Since I constantly forgot what the correct arg name is,
let's add it explicitly to the README.

R=dpranke@google.com

Change-Id: Ic91cbf02e7d14cb6b3bf44e0419a364825f976bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/2891831
Auto-Submit: Tim van der Lippe <tvanderlippe@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>
1 file changed
tree: b2ddb75d7c932814b9ae579913ad321843c89c13
  1. infra/
  2. recipes/
  3. scripts/
  4. site_config/
  5. .gitattributes
  6. .gitignore
  7. .style.yapf
  8. .vpython
  9. .yapfignore
  10. codereview.settings
  11. CROS_OWNERS
  12. DEPS
  13. environment.cfg.py
  14. LICENSE
  15. OWNERS
  16. PRESUBMIT.py
  17. README.md
  18. WATCHLISTS
README.md

Recipes

If you're here to make a change to ‘recipes’ (the code located in the recipes directory), please take a look at the README for more information pertaining to recipes.

Style

The preferred style is PEP8 with two-space indent; that is, the Chromium Python style. Functions use lowercase_with_underscores, with the exception of the special functions RunSteps and RunTests in recipes. Use yapf (git cl format --no-clang-format) to autoformat new code.