**doc/operations/feature_flags.md:**

Adds documentation for this new feature.

**app/assets/javascripts/feature_flags/constants.js:**

Adds flexible rollout strategy.

**app/assets/javascripts/feature_flags/utils.js:**

Adds flexible rollout strategy.

**app/assets/javascripts/feature_flags/components/strategy.vue:**

- Removes some cruft.
- Adds a Tip to suggest using flexible rollout instead of users rollout.
- Moves form description elements to the correct location.

**app/assets/javascripts/feature_flags/components/
strategy_parameters.vue:**

Adds flexible rollout strategy.

**app/assets/javascripts/feature_flags/components/strategies/
flexible_rollout.vue:**

Implementation of the new flexible rollout strategy.

**app/assets/javascripts/feature_flags/components/strategies/
gitlab_user_list.vue:**

Don't show description when there's an error.

**app/assets/javascripts/feature_flags/components/strategies/
percent_rollout.vue:**

Default to 100%.

**spec/frontend/feature_flags/mock_data.js:**

Adds flexible rollout strategy.

**spec/frontend/feature_flags/components/strategy_spec.js:**

Adds flexible rollout strategy.

**spec/frontend/feature_flags/components/strategies/
flexible_rollout_spec.js:**

Spec tests for the new flexible rollout strategy.

**locale/gitlab.pot:**

I18n updates.

**changelogs/unreleased/feature-flags-flexible-rollout-ux.yml:**

Changelog.