Add documentation for OneDrive

source/_integrations/onedrive.markdown

@@ -0,0 +1,67 @@
+---
+title: OneDrive
+description: Instructions on how to setup OneDrive to be used with backups.
+ha_release: 2025.2
+ha_category:
+  - Backup
+ha_iot_class: Cloud Polling
+ha_config_flow: true
+ha_domain: onedrive
+ha_codeowners:
+  - '@zweckj'
+ha_integration_type: service
+related:
+  - docs: /common-tasks/general/#backups
+    title: Backups
+---
+
+This integration allows you to use [OneDrive](https://www.microsoft.com/en-us/microsoft-365/onedrive/online-cloud-storage) for [Home Assistant Backups](/common-tasks/general/#backups).
+
+Backups will be created in a folder called `Home Assistant\backups_<id>` in the `App Folder` of your OneDrive.
+`id` is part of your Home Assistant instance's unique id to allow backups from multiple instances to the same OneDrive account.
+The integration only has access to an application specific `Home Assistant` folder in the `App Folder` and cannot access to any other parts of your OneDrive.
+
+{% note %}
+Because of an [issue in the Graph API](https://github.com/OneDrive/onedrive-api-docs/issues/1866), the application-specific folder sometimes is called `Graph` instead of `Home Assistant`.
+{% endnote %}
+
+{% include integrations/config_flow.md %}
+{% configuration_basic %}
+Client ID:
+  description: "Application ID of the app registration to be used with the integration. Uses Home Assistant provided by default."
+Client secret:
+  description: "Application secret for the app registration. Uses Home Assistant provided by default."
+
+{% endconfiguration_basic %}
+
+## Requested permissions by the integration
+
+The integration will request the following permissions on your OneDrive for the integration to work:
+
+- `Files.ReadWrite.AppFolder`: Grants the application permission to read and write in its own, app-specific folder inside your OneDrive
+- `offline_access`: Grants the application permission to refresh its authentication token without requiring your manual intervention
+- `openid`: Grants the application permission to read basic information, e.g. if you have a OneDrive
+
+
+<img src='/images/integrations/onedrive/onedrive-permissions.png' alt='Lists of permissions that the application will request.'>
+
+
+## Getting application credentials
+
+This integration comes with a predefined set of [application credentials](https://www.home-assistant.io/integrations/application_credentials/) through Home Assistant account linking. 
+Nobody will ever have access to your data except you, as the app does not have permission to do anything on its own. It only works with a signed-in user (it only has `delegated` not `application permissions`). 
+However, if you want to use your own credentials, follow [this guide](https://learn.microsoft.com/en-us/entra/identity-platform/quickstart-register-app?tabs=certificate) to create your own client ID and secret.
+
+{% note %}
+You will need an Azure tenant with an active Azure subscription to create your own client credentials.
+{% endnote %}
+
+## Known limitations
+
+- Only personal OneDrives are supported at the moment.
+
+## Removing the integration
+
+This integration follows standard integration removal. No extra steps are required.
+
+{% include integrations/remove_device_service.md %}