Document Open Media Vault WebDAV setup (#694)

* Create README.md

Create documentation on how to add WebDAV access to Open Media Vault and use it on Remotely Save

* Update README.md

Add link to Open Media Vault WebDAV documentation.

README.md

@@ -111,6 +111,7 @@ Additionally, the plugin author may occasionally visit Obsidian official forum a
   - [Synology webdav server](./docs/remote_services/webdav_synology_webdav_server/README.md) | [群晖 webdav server](./docs/remote_services/webdav_synology_webdav_server/README.zh-cn.md)
   - [AList（中文）](./docs/remote_services/webdav_alist/README.zh-cn.md) | [AList (English)](./docs/remote_services/webdav_alist/README.md)
   - [坚果云](./docs/remote_services/webdav_jianguoyun/README.zh-cn.md) | [JianGuoYun/NutStore](./docs/remote_services/webdav_jianguoyun/README.md)
+  - [Open Media Vault](./docs/remote_services/webdav_openmediavault/README.md)
 - Very old version of Obsidian needs [configuring CORS](./docs/remote_services/webdav_general/webav_cors.md).
 - Your data would be synced to a `${vaultName}` sub folder on your webdav server.
 - Password-based end-to-end encryption is also supported. But please be aware that **the vault name itself is not encrypted**.

docs/remote_services/webdav_openmediavault/README.md

@@ -0,0 +1,21 @@
+# Open Media Vault WebDAV
+
+## Link 
+https://www.openmediavault.org
+
+## Steps
+
+1. In Open Media Vault's UI, install the WebDAV plugin:
+   * System → Plugins → openmediavault-webdav
+2. Create a new Shared Folder
+   * Storage → Shared Folders → Create
+3. Enable WebDAV server
+   * Services → WedDAV → Enable → Select previously created Shared Folder
+4. Make sure Group is "webdav-users"
+5. Add {your username} to "webdav-users" group
+   * Users → Groups → webdav-users → Edit → Members
+6. Set folder permissions
+   * Storage → Shared Folders select the corresponding shared folder → Permissions → Set both {your username} and "webdav-users" group to "Read/Write" permissions
+7. Back to Shared Folders, set specific Access Control List permissions
+   * Select the shared folder → Access Control List → set {your username}, "webdav-users" and "www-data" to "Read/Write" permissions
+8. Install Remotely Save in Obsidian, select WebDAV, add the URL http://[your-server-ip]/webdav, use your user credentials and connect.