use wget to get repo key

README.md

@@ -46,7 +46,7 @@ The Source Installation instructions should be used if you need the very latest
 On Ubuntu systems, `apt-get` can be used to install `sdformat`:
 ```sh
 sudo sh -c 'echo "deb http://packages.osrfoundation.org/gazebo/ubuntu-stable `lsb_release -cs` main" > /etc/apt/sources.list.d/gazebo-stable.list'
-sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys D2486D2DD83DB69272AFE98867170598AF249743
+wget http://packages.osrfoundation.org/gazebo.key -O - | sudo apt-key add -
 sudo apt-get update
 
 sudo apt install libsdformat<#>-dev libsdformat<#>