**config/feature_flags/development/
  environment_auto_stop_start_on_create.yml**:

Adds a development feature flag for this change.

**doc/ci/yaml/README.md:**

Updates documentation on how auto_stop_in works.

**lib/gitlab/ci/pipeline/seed/environment.rb:**

Updates the seed to set auto_stop_at from auto_stop_in.

**spec/lib/gitlab/ci/pipeline/seed/environment_spec.rb:**

Update spec tests for the environment seed.