Add default path prefix when using working-directory flag

Add default path prefix when using working-directory flag

don't add --new args if not requested

Support `only-new-issues` (#19)

Fixes #16

docs: add working-directory to README

mark the action as stable: v0 -> v1

Merge pull request #13 from golangci/feature/action-config

use action config, don't require github token

docs: fix version, @v0 doesn't work

Merge pull request #10 from golangci/feature/fix-github-token

docs: recommend using GITHUB_TOKEN

dev: shorten description