Remove demo for Olelo.

The server previously hosting the demo for Olelo does not respond anymore, so I've removed the demo-link.

README.md

@@ -1478,7 +1478,7 @@ See also [Documentation Generators](#documentation-generators), [Wikimatrix](htt
 - [jingo](https://github.com/claudioc/jingo) - Git based wiki engine written for node.js, with a decent design, a search capability and good typography. `MIT` `Nodejs`
 - [Mediawiki](https://www.mediawiki.org/wiki/MediaWiki) - MediaWiki is a free and open-source wiki software package written in PHP. It serves as the platform for Wikipedia and the other Wikimedia projects, used by hundreds of millions of people each month. ([Demo](https://en.wikipedia.org/wiki/Main_Page), ([Source Code](https://phabricator.wikimedia.org/diffusion/MW/)) `GPL-2.0` `PHP`
 - [MoinMoin](https://moinmo.in/) - Advanced, easy to use and extensible WikiEngine with a large community of users. ([Source Code](http://hg.moinmo.in/moin)) `GPL-2.0` `Python`
-- [Olelo](https://github.com/minad/olelo) - Olelo is a wiki that stores pages in a Git repository, supports many markup styles and has an extensible, hackable architecture. ([Demo](http://gitwiki.org/)) `MIT` `Ruby`
+- [Olelo](https://github.com/minad/olelo) - Olelo is a wiki that stores pages in a Git repository, supports many markup styles and has an extensible, hackable architecture. `MIT` `Ruby`
 - [Outline](https://www.getoutline.com/) `⚠` - An open, extensible, wiki for your team built using React and Node.js. ([Source Code](https://github.com/outline/outline)) `BSD-3-Clause` `Nodejs`
 - [Pepperminty Wiki](https://github.com/sbrl/Pepperminty-Wiki) - Complete markdown-powered wiki contained in a single PHP file. ([Demo](https://starbeamrainbowlabs.com/labs/peppermint/build/)) `MPL-2.0` `PHP`
 - [PineDocs](https://github.com/xy2z/PineDocs) - Simple, fast, customizable and lightweight site for browsing files. `GPL-3.0` `PHP`