Merge branch '519540-add-csv-functionality-back-into-docs' into 'master'

Add CSV functionality back into docs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/182090



Merged-by: James Nutt <jnutt@gitlab.com>
Approved-by: James Nutt <jnutt@gitlab.com>
Reviewed-by: James Nutt <jnutt@gitlab.com>
Co-authored-by: Martin Wortschack <mwortschack@gitlab.com>

app/assets/javascripts/members/placeholders/components/csv_upload_modal.vue

@@ -87,7 +87,7 @@ export default {
   },
   dropzoneAllowList: ['.csv'],
   docsLink: helpPagePath('user/project/import/_index', {
-    anchor: 'reassign-contributions-and-memberships',
+    anchor: 'request-reassignment-by-using-a-csv-file',
   }),
   i18n: {
     description: s__(

doc/user/project/import/_index.md

@@ -274,10 +274,13 @@ Users with the Owner role for a top-level group can reassign contributions and m
 from placeholder users to existing active (non-bot) users.
 On the destination instance, users with the Owner role for a top-level group can:
 
-- Request users to accept reassignment of contributions and membership [in the UI](#request-reassignment-in-ui).
-  The reassignment process starts only after the selected user [accepts the reassignment request](#accept-contribution-reassignment),
-  which is sent to them by email.
-- Choose not to reassign contributions and memberships, and [keep them with placeholder users](#keep-as-placeholder).
+- Request users to review reassignment of contributions and memberships [in the UI](#request-reassignment-in-ui)
+  or [through a CSV file](#request-reassignment-by-using-a-csv-file).
+  For a large number of placeholder users, you should use a CSV file.
+  In both cases, users receive a request by email to accept or reject the reassignment.
+  The reassignment starts only after the selected user
+  [accepts the reassignment request](#accept-contribution-reassignment).
+- Choose not to reassign contributions and memberships and [keep them assigned to placeholder users](#keep-as-placeholder).
 
 All the contributions initially assigned to a single placeholder user can only be reassigned to a single active regular
 user on the destination instance. The contributions assigned to a single placeholder user cannot be split among multiple
@@ -353,6 +356,56 @@ Contributions of only one placeholder user can be reassigned to an active non-bo
 
 Before a user accepts the reassignment, you can [cancel the request](#cancel-reassignment-request).
 
+#### Request reassignment by using a CSV file
+
+{{< history >}}
+
+- [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/455901) in GitLab 17.10 [with a flag](../../../administration/feature_flags.md) named `importer_user_mapping_reassignment_csv`. Disabled by default.
+
+{{< /history >}}
+
+{{< alert type="flag" >}}
+
+The availability of this feature is controlled by a feature flag.
+For more information, see the history.
+This feature is available for testing, but not ready for production use.
+
+{{< /alert >}}
+
+Prerequisites:
+
+- You must have the Owner role for the group.
+
+For a large number of placeholder users, you might want to
+reassign contributions and memberships by using a CSV file.
+You can download a prefilled CSV template with the following information.
+For example:
+
+| Source host          | Import type | Source user identifier | Source user name | Source username |
+|----------------------|-------------|------------------------|------------------|-----------------|
+| `gitlab.example.com` | `gitlab`    | `alice`                | `Alice Coder`    | `a.coer`        |
+
+Do not update **Source host**, **Import type**, or **Source user identifier**.
+This information locates the corresponding database record
+after you've uploaded the completed CSV file.
+**Source user name** and **Source username** identify the source user
+and are not used after you've uploaded the CSV file.
+
+To request reassignment of contributions and memberships by using a CSV file:
+
+1. On the left sidebar, select **Search or go to** and find your group.
+1. Select **Manage > Members**.
+1. Select the **Placeholders** tab.
+1. Select **Reassign with CSV**.
+1. Download the prefilled CSV template.
+1. In **GitLab username** or **GitLab public email**, enter the username or email address
+   of the GitLab user on the destination instance.
+   You can use only public email addresses for reassignment.
+1. Upload the completed CSV file.
+1. Select **Reassign**.
+
+Users receive an email to review and accept any contributions reassigned to them.
+
 #### Keep as placeholder
 
 You might not want to reassign contributions and memberships to users on the destination instance. For example, you