Add Zim wiki to the selfhosted wiki section

README.md

@@ -1540,6 +1540,7 @@ See also [Documentation Generators](#documentation-generators), [Wikimatrix](htt
 - [Wiki.js](https://wiki.js.org/) - Modern, lightweight and powerful wiki app built on NodeJS, Git and Markdown. ([Demo](https://docs.requarks.io)) `AGPL-3.0` `Nodejs`
 - [WiKiss](http://wikiss.tuxfamily.org/) - Wiki, simple to use and install. ([Source Code](https://svnweb.tuxfamily.org/listing.php?repname=wikiss/svn&path=%2F&sc=0)) `GPL-2.0` `PHP`
 - [XWiki](http://www.xwiki.org) - Second generation wiki that allows the user to extend its functionalities with a powerful extension-based architecture. ([Demo](http://playground.xwiki.org), [Source Code](https://github.com/xwiki/xwiki-platform)) `LGPL-2.1` `Java`
+- [Zim](https://zim-wiki.org/) - Graphical text editor used to maintain a collection of wiki pages. Each page can contain links to other pages, simple formatting and images.  ([Source Code](https://github.com/zim-desktop-wiki/zim-desktop-wiki)) `GPL-2.0` `Python`
 
 ## Self-hosting Solutions