test-repo/changelog_unreleased/cli/pr-8829.md

Added --ignore-unknown(alias -u) flag (#8829 by @fisker)

# Prettier stable
npx prettier * --check
Checking formatting...
foo.unknown[error] No parser could be inferred for file: foo.unknown
All matched files use Prettier code style!

# Prettier master
npx prettier * --check --ignore-unknown
Checking formatting...
All matched files use Prettier code style!