Updated Install on Linux (markdown)

Install-on-Linux.md

@@ -1,6 +1,7 @@
 1. Go to www.rambox.pro and download zip file for Linux.
 2. Unzip downloaded file. Be sure to extract all the files inside a new folder called **Rambox** for example.
 3. In a Terminal, type: `chmod +x Rambox`.
-4. Last, in the same Terminal type: `./Rambox`.
+4. Then, we have to install a library (probably missing) to allow tray icon. So type `sudo apt-get install libappindicator1`.
+5. Last, in the same Terminal type: `./Rambox`.
 
 There is also a video tutorial that may help. Check out [HERE](https://www.youtube.com/watch?v=SH6o92b7FlA).