Add "Joplin" topic

Author: laurent22

topics/joplin/index.md

@@ -0,0 +1,12 @@
+---
+created_by: Laurent Cozic
+display_name: Joplin
+github_url: https://github.com/laurent22/joplin
+logo: joplin.png
+released: '2016'
+short_description: Secure note-taking app with synchornisation capabilities
+topic: joplin
+url: https://joplinapp.org
+wikipedia_url: https://en.wikipedia.org/wiki/Joplin_(software)
+---
+Joplin is a note-taking app for Windows, macOS, Linux, Android and iOS. It focuses on security and extensibility.