SDFormat10 package not available on Ubuntu

[varunagrawal]

Environment

• OS Version: 20.04
• Binary build for SDFormat10.

Description

• Expected behavior: As per the README, running apt-get install libsdformat10 should install the SDFormat package from Ubuntu's repositories.
• Actual behavior: apt-get cannot find the package.

Steps to reproduce

1. Take a fresh version of Ubuntu 20.04 (I used a docker image to verify this).
2. Follow the README and run sudo apt-get -y install libsdformat10.
3. See the failure.

Output

root@447c4bd99237:/# apt -y install sdformat10
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package sdformat10

[varunagrawal]

My guess is that we need to run these extra commands before trying to install:

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
sudo apt-get update

sudo apt-get -y install libsdformat10  # This should work now

If so, this should be added to the README.

[azeey]

Yes, we currently only have libsdformat6 on Ubuntu 20.04, so if other versions are needed, it's necessary to add the packages.osrfoundation.org repo. Do you mind creating a PR with your suggestion?