Add documentation for new WebDAV integration (#37365)

* Add documentation for new WebDAV integration

* Add missing verify ssl

* Fix

* Update source/_integrations/webdav.markdown

Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>

---------

Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>

source/_integrations/webdav.markdown

@@ -0,0 +1,50 @@
+---
+title: WebDAV
+description: Instructions on how to setup a WebDAV location to be used with backups.
+ha_release: 2025.3
+ha_category:
+  - Backup
+ha_iot_class: Cloud Polling
+ha_config_flow: true
+ha_domain: webdav
+ha_codeowners:
+  - '@jpbede'
+ha_integration_type: service
+related:
+  - docs: /common-tasks/general/#backups
+    title: Backups
+ha_quality_scale: bronze
+---
+
+This integration allows you to use a [WebDAV](https://en.wikipedia.org/wiki/WebDAV) compatible location for [Home Assistant Backups](/common-tasks/general/#backups).
+
+## Installation
+
+{% include integrations/config_flow.md %}
+{% configuration_basic %}
+URL:
+  description: "URL of the WebDAV server. Common examples are provided below."
+Username:
+  description: "Username for the WebDAV server."
+Password:
+  description: "Password for the WebDAV server."
+Backup path:
+  description: "Path to the folder where the backups should be stored. The path is relative to the root of the WebDAV server."
+Verify SSL:
+  description: "Verify the SSL certificate of the WebDAV server."
+{% endconfiguration_basic %}
+
+### Common WebDAV URLs
+
+- [Nextcloud](https://nextcloud.com/): `https://<your-nextcloud-domain>/remote.php/dav/files/<your-username>/`
+- [Owncloud](https://owncloud.com/): `https://<your-owncloud-domain>/remote.php/dav/files/<your-username>/`
+- [Hetzner Storage Box](https://www.hetzner.com/storage/storage-box): `https://<username>.your-storagebox.de`
+- [Strato HiDrive](https://www.strato.de/): `https://webdav.hidrive.strato.com`
+
+## Removing the integration
+
+This integration follows standard integration removal. No extra steps are required.
+
+{% include integrations/remove_device_service.md %}
+
+- If you remove the integration, the backup folder is not automatically deleted. You have to manually delete it.