message: docs/stability-index: add integrations package
diff: @@ -178,6 +178,17 @@ Internal CLI utility for running e2e tests.
  Stability: `N/A`
  +### `integration` [GitHub](https://github.com/backstage/backstage/tree/master/packages/integration/)
  +
  +Provides shared utilities for managing integrations towards different types of
  +third party systems. This package is currently internal and its functionality
  +will likely be exposed via separate APIs in the future.
  +
  +Some of the functionality in this package is not available elsewhere yes, so if
  +it's necessary it can be used, but there will be breaking changes.
  +
  +Stability: `0`
  +
  ### `storybook` [GitHub](https://github.com/backstage/backstage/tree/master/packages/storybook/)
  Internal storybook build for publishing stories to
  