add docsify xmind plugin (#277)

Co-authored-by: Lu Fei <52o@qq52o.cn>

README.md

@@ -171,6 +171,7 @@ A curated list of awesome things related to [docsify](https://docsify.js.org)
 - [docsify-pagination](https://github.com/imyelo/docsify-pagination) - Pagination for docsify [@imyelo](https://github.com/imyelo).
 - [docsify-plantuml](https://github.com/imyelo/docsify-plantuml) - PlantUML for docsify @imyelo.
 - [docsify-puml](https://github.com/indieatom/docsify-puml) - Docsify plugin to parse PlantUML content [@indieatom](https://github.com/indieatom).
+- [docsify-xmind](https://github.com/AntHubTC/docsify-xmind) - Docsify plugin to preview of your xmind file [@AntHubTC](https://github.com/AntHubTC).
 - [docsify-copy-code](https://github.com/jperasmus/docsify-copy-code) - A docsify plugin that copies Markdown code block to your clipboard [@jperasmus](https://github.com/jperasmus).
 - [docsify-demo-box-vue](https://github.com/njleonzhang/docsify-demo-box-vue) - Write Vue demo in docsify with instant preview and jsfiddle integration [@njleonzhang](https://github.com/njleonzhang/).
 - [docsify-demo-box-react](https://github.com/njleonzhang/docsify-demo-box-react) - Write React jsx demo in docsify with instant preview and jsfiddle integration @njleonzhang.