Update link to feature flag docs

doc/api/README.md

@@ -390,7 +390,7 @@ CAUTION: **Caution:**
 For performance reasons since
 [GitLab 11.8](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/23931)
 and **behind the `api_kaminari_count_with_limit`
-[feature flag](../development/feature_flags.md)**, if the number of resources is
+[feature flag](../development/feature_flags/index.md)**, if the number of resources is
 more than 10,000, the `X-Total` and `X-Total-Pages` headers as well as the
 `rel="last"` `Link` are not present in the response headers.
 

doc/development/README.md

@@ -63,7 +63,7 @@ Complementary reads:
   styleguide if you are contributing to the [GraphQL API](../api/graphql/index.md)
 - [Sidekiq guidelines](sidekiq_style_guide.md) for working with Sidekiq workers
 - [Working with Gitaly](gitaly.md)
-- [Manage feature flags](feature_flags.md)
+- [Manage feature flags](feature_flags/index.md)
 - [Licensed feature availability](licensed_feature_availability.md)
 - [View sent emails or preview mailers](emails.md)
 - [Shell commands](shell_commands.md) in the GitLab codebase