doc: Add cloudron as an installation option

fixes #2002

doc/cloudron.markdown

@@ -0,0 +1,28 @@
+How to run Kanboard on Cloudron
+================================
+
+[Cloudron](https://cloudron.io) is a private smartserver on which you can install web
+apps like Kanboard. You can install Kanboard into a custom domain and each
+installation is backed up and kept up-to-date with Kanboard releases automatically.
+
+[![Install](https://cloudron.io/img/button.svg)](https://cloudron.io/button.html?app=net.kanboard.cloudronapp)
+
+Accounts
+--------
+
+The app integrates tightly with the Cloudron User Management (via LDAP). Only
+Cloudron users can access the Kanboard. In addition, any Cloudron administrator
+becomes a Kanboard administrator automatically.
+
+Installing Plugins
+------------------
+
+Plugins can be installed and configured using the [Cloudron CLI](https://cloudron.io/references/cli.html)
+tool. See the [app description](https://cloudron.io/appstore.html?app=net.kanboard.cloudronapp) for
+more information.
+
+Application Source code
+----------------------
+
+The source code for the Cloudron app is [here](https://github.com/cloudron-io/kanboard-app).
+

doc/index.markdown

@@ -100,6 +100,7 @@ Technical details
 - [Installation on Heroku](heroku.markdown)
 - [Run Kanboard with Docker](docker.markdown)
 - [Run Kanboard with Vagrant](vagrant.markdown)
+- [Run Kanboard on Cloudron](cloudron.markdown)
 
 ### Configuration