The ombi repo doesn't have an i386 version created, so on Ubuntu 16.04 you'd get an error. This change limits the repo to the two architectures that are included.

Installation.md

@@ -31,11 +31,11 @@ Alternatively, you can copy nssm.exe to your %WINDIR%\system32 (C:\Windows\Syste
 1. Add the apt repository to the apt sources list:
    * _If you would like stable releases execute:_  
    ```
-   echo "deb http://repo.ombi.turd.me/stable/ jessie main"  | sudo tee  /etc/apt/sources.list.d/ombi.list > /dev/null
+   echo "deb [arch=amd64,armhf] http://repo.ombi.turd.me/stable/ jessie main"  | sudo tee  /etc/apt/sources.list.d/ombi.list > /dev/null
    ```  
    * _If you would like development releases execute this instead:_  
    ```
-   echo "deb http://repo.ombi.turd.me/develop/ jessie main" | sudo tee  /etc/apt/sources.list.d/ombi.list > /dev/null
+   echo "deb [arch=amd64,armhf] http://repo.ombi.turd.me/develop/ jessie main" | sudo tee  /etc/apt/sources.list.d/ombi.list > /dev/null
    ```
 
 1. Ombi uses a signed repository. This means packages get validated before installation. So, to safely download and install Ombi packages the Ombi key needs to be installed: