[ubookmark] add demo link with IPv4 support

README.md

@@ -235,7 +235,7 @@ See also [Static Site Generators](#static-site-generators), [Content Management
 - [Shaarli](https://github.com/shaarli/Shaarli) - Personal, minimalist, super-fast, no-database bookmarking and link sharing platform. ([Demo](https://demo.shaarli.org)) `Zlib` `PHP`
 - [Shiori](https://github.com/RadhiFadlillah/shiori) - Simple bookmark manager built with Go. `MIT` `Go`
 - [unmark](https://github.com/plainmade/unmark) - Open source to do app for links. `MIT` `PHP`
-- [ubookmark](https://ungleich.ch/u/projects/ubookmark/) - LDAP enabled bookmarking service. ([Source Code](https://code.ungleich.ch/ungleich-public/ubookmark/)) `GPL-2.0` `Python`
+- [ubookmark](https://ungleich.ch/u/projects/ubookmark/) - LDAP enabled bookmarking service. ([Demo](https://ipv6.blog), [Source Code](https://code.ungleich.ch/ungleich-public/ubookmark/)) `GPL-2.0` `Python`
 - [xBrowserSync](https://www.xbrowsersync.org) - Open source tool for syncing browser data between browsers and devices. ([Source Code](https://github.com/xBrowserSync)) `MIT` `Nodejs`
 - [ymarks](https://bitbucket.org/ymarks/ymarks-server) - Keep your browser's bookmarks synchronized without limiting yourself to one provider. `WTFPL` `C`