refactor: renovateFork -> includeForks

docs/local-development.md

lib/config/cli.js

lib/config/definitions.js

lib/config/migration.js

lib/platform/github/index.js

lib/workers/repository/configured.js

lib/workers/repository/onboarding/branch/index.js

test/config/__snapshots__/migration.spec.js.snap

test/config/migration.spec.js

website/docs/configuration-options.md