…ing (#350)

* fix: use `NODE_OPTIONS` instead of calling `node` directly for debugging

* docs: add changelog entry

* refactor: don't use `+=`

* ci: update `actions/checkout` to v3

* ci: update `actions/setup-node` to v3

* ci: disable persisted git credentials for improved security

* ci: update `actions/checkout` to v4

* test: improve consistency of example names and general layout

* test: use `Dir.chdir` with a block instead of `ensure`

* test: remove unused parameter

…343)

* feat: support passing config to `generateWebpackConfig` for merging

* fix: update types

* docs: update more uses of `merge`

* test: update dummy app

* fix: throw if multiple configs are provided

* docs: add CHANGELOG entry

* docs: improve readme to make it clearer where the webpack config file lives

* refactor: explicitly check length against `0`

`shakapacker.yml` has `source_entry_path: packs` instead of `/` by default.