Add notes about clear_index_status rake task

doc/integration/elasticsearch.md

@@ -441,7 +441,7 @@ The following are some available Rake tasks:
 | [`sudo gitlab-rake gitlab:elastic:index`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)                            | Enables Elasticsearch indexing and run `gitlab:elastic:create_empty_index`, `gitlab:elastic:clear_index_status`, `gitlab:elastic:index_projects`, and `gitlab:elastic:index_snippets`.                          |
 | [`sudo gitlab-rake gitlab:elastic:index_projects`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)                   | Iterates over all projects and queues Sidekiq jobs to index them in the background.                                                                                                       |
 | [`sudo gitlab-rake gitlab:elastic:index_projects_status`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)            | Determines the overall status of the indexing. It is done by counting the total number of indexed projects, dividing by a count of the total number of projects, then multiplying by 100. |
-| [`sudo gitlab-rake gitlab:elastic:clear_index_status`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)               | Deletes all instances of IndexStatus for all projects.                                                                                                                                    |
+| [`sudo gitlab-rake gitlab:elastic:clear_index_status`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)               | Deletes all instances of IndexStatus for all projects. Note that this command will result in a complete wipe of the index, and it should be used with caution.                                                                                              |
 | [`sudo gitlab-rake gitlab:elastic:create_empty_index[<TARGET_NAME>]`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake) | Generates an empty index and assigns an alias for it on the Elasticsearch side only if it doesn't already exist.                                                                                                      |
 | [`sudo gitlab-rake gitlab:elastic:delete_index[<TARGET_NAME>]`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)       | Removes the GitLab index and alias (if exists) on the Elasticsearch instance.                                                                                                                                   |
 | [`sudo gitlab-rake gitlab:elastic:recreate_index[<TARGET_NAME>]`](https://gitlab.com/gitlab-org/gitlab/blob/master/ee/lib/tasks/gitlab/elastic.rake)     | Wrapper task for `gitlab:elastic:delete_index[<TARGET_NAME>]` and `gitlab:elastic:create_empty_index[<TARGET_NAME>]`.                                                                       |