removing reference to Debian 9

Author: raisalitch

articles/iot-edge/troubleshoot-common-errors.md

@@ -507,7 +507,7 @@ The security daemon fails to start and module containers aren't created. The `ed
 
 **Root cause:**
 
-For all Linux distros except CentOS 7 (including Debian 9), IoT Edge's default configuration is to use `systemd` socket activation. A permission error happens if you change the configuration file to not use socket activation but leave the URLs as `/var/run/iotedge/*.sock`, since the `iotedge` user can't write to `/var/run/iotedge` meaning it can't unlock and mount the sockets itself. 
+For all Linux distros except CentOS 7, IoT Edge's default configuration is to use `systemd` socket activation. A permission error happens if you change the configuration file to not use socket activation but leave the URLs as `/var/run/iotedge/*.sock`, since the `iotedge` user can't write to `/var/run/iotedge` meaning it can't unlock and mount the sockets itself. 
 
 **Resolution:**