Add user creation documentation

doc/administration/index.md

@@ -104,6 +104,7 @@ Learn how to install, configure, update, and maintain your GitLab instance.
 
 ## User settings and permissions
 
+- [Creating users](../user/profile/account/create_accounts.md): Create users manually or through authentication integrations.
 - [Libravatar](../customization/libravatar.md): Use Libravatar instead of Gravatar for user avatars.
 - [Sign-up restrictions](../user/admin_area/settings/sign_up_restrictions.md): block email addresses of specific domains, or whitelist only specific domains.
 - [Access restrictions](../user/admin_area/settings/visibility_and_access_controls.md#enabled-git-access-protocols): Define which Git access protocols can be used to talk to GitLab (SSH, HTTP, HTTPS).

doc/user/profile/account/create_accounts.md

+---
+type: reference
+---
+
+# Creating users **(CORE ONLY)**
+
+You can create users:
+
+- Manually through the sign in page or Admin Area.
+- Automatically through user authentication integrations.
+
+## Create users on sign in page
+
+If you have [sign-up enabled](../../admin_area/settings/sign_up_restrictions.md), users can create their own accounts using the **Register** tab on the sign in page.
+
+![Register Tab](img/register_tab.png)
+
+## Create users in admin area
+
+As an admin user, you can manually create users by:
+
+1. Navigating to **Admin Area > Overview > Users** (`/admin/users` page).
+1. Selecting the **New User** button.
+
+You can also [create users through the API](../../../api/users.md) as an admin.
+
+![Admin User Button](img/admin_user_button.png)
+
+![Admin User Form](img/admin_user_form.png)
+
+## Create users through integrations
+
+Users will be:
+
+- Automatically created upon first login with the [LDAP integration](../../../administration/auth/ldap.md).
+- Created when first logging in via an [OmniAuth provider](../../../integration/omniauth.md) if the `allow_single_sign_on` setting is present.

doc/user/profile/index.md

@@ -8,6 +8,10 @@ Each GitLab account has a user profile, and settings. Your [profile](#user-profi
 contains information about you, and your GitLab activity. Your [settings](#profile-settings)
 allow you to customize some aspects of GitLab to suit yourself.
 
+## Creating users
+
+There are several ways to create users on GitLab. See the [creating users documentation](account/create_accounts.md) for more details.
+
 ## Signing in
 
 There are several ways to sign into your GitLab account.