remove cowyo (#3505)

- unmaintained since 2020
- ref. https://github.com/awesome-selfhosted/awesome-selfhosted/issues/3499

README.md

@@ -2086,7 +2086,6 @@ _See also: [Wikimatrix](https://www.wikimatrix.org/), [Wiki Engines - WikiIndex]
 
 - [AmuseWiki](https://amusewiki.org/) - Amusewiki is based on the Emacs Muse markup, remaining mostly compatible with the original implementation. It can work as a read-only site, as a moderated wiki, or as a fully open wiki or even as a private site. ([Demo](https://sandbox.amusewiki.org), [Source Code](https://github.com/melmothx/amusewiki)) `GPL-1.0` `Perl/Docker`
 - [BookStack](https://www.bookstackapp.com/) - BookStack is a simple, self-hosted, easy-to-use platform for organizing and storing information. It allows for documentation to be stored in a book like fashion. ([Demo](https://www.bookstackapp.com/#demo), [Source Code](https://github.com/BookStackApp/BookStack)) `MIT` `PHP`
-- [Cowyo](https://github.com/schollz/cowyo) - Cowyo is a feature-rich wiki for minimalists. ([Demo](https://cowyo.com)) `MIT` `Go`
 - [django-wiki](https://github.com/django-wiki/django-wiki) - Wiki system with complex functionality for simple integration and a superb interface. Store your knowledge with style: Use django models. ([Demo](https://demo.django-wiki.org/)) `GPL-3.0` `Python`
 - [Documize](https://documize.com) - Modern Docs + Wiki software with built-in workflow, single binary executable, just bring MySQL/Percona. ([Source Code](https://github.com/documize/community)) `AGPL-3.0` `Go`
 - [Dokuwiki](https://www.dokuwiki.org/DokuWiki) - Easy to use, lightweight, standards-compliant wiki engine with a simple syntax allowing reading the data outside the wiki. All data is stored in plain text files, therefore no database is required. ([Source Code](https://github.com/splitbrain/dokuwiki)) `GPL-2.0` `PHP`