Add WebDAV settings reference to README

Documents allowed users, password sync, www-data folder permissions,
and the no-toggle limitation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -138,6 +138,37 @@ find /srv/yourshare/.recycle -mtime +30 -delete
 
 ---
 
+### WebDAV share settings
+
+WebDAV is served by Apache on port 80. Shares are accessible at `http://<nas-ip>/dav/<name>`. Auth is HTTP Basic (username + password), managed via an htpasswd file that MicroNAS keeps in sync with the Users tab automatically.
+
+**Allowed Users** — space-separated list of usernames who can access this share. Leave empty to allow all users in the htpasswd file (anyone with a MicroNAS account). Groups (`@groupname`) are not supported for WebDAV — list individual usernames.
+
+```
+alice bob       → only alice and bob
+                → (empty) anyone with a valid MicroNAS password
+```
+
+**Password sync** — when you create a user or change a password in the Users tab, MicroNAS automatically updates the WebDAV htpasswd file. Users created before WebDAV was installed need their password changed once to register.
+
+**Folder Permissions** — same as SMB: owner, group, and mode on the actual folder on disk. WebDAV clients write files as the Apache process user (`www-data` by default), so the folder needs to be writable by `www-data` or you need to set `force group` equivalent at the OS level. Simplest setup:
+
+```bash
+chown www-data:www-data /srv/yourfolder
+chmod 775 /srv/yourfolder
+```
+
+Or give your group write access and add `www-data` to that group:
+
+```bash
+usermod -aG family www-data
+# Then set folder: group=family, mode=775
+```
+
+**No toggle/disable** — WebDAV shares can only be created or deleted, not temporarily disabled. To block access temporarily, remove the users or delete and recreate the share.
+
+---
+
 ### NFS export settings
 
 NFS has no username/password concept — access is controlled by IP/hostname only (the Clients field). Once connected, the client's UID/GID is passed to the server and Linux file permissions apply normally.