Cannot install Docker on Ubuntu 18.04

I tried installing Docker using this guide as well as many others but every time I needed to add the PPA with this command sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" I get this error

E: The repository 'https://download.docker.com/linux/ubuntu juno Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.

It may be because since I am using Elementary OS, which is a distribution of Ubuntu and it tries to get the “Juno” release (which is the name of the ElementaryOS release) but it does not find it since it is not a Ubuntu release name hence the fact that it says

juno Release' does not have a Release

But I am not sure at all.
Please help

The correct command would be:

sudo add-apt-repository “deb [arch=amd64] Index of linux/ubuntu/ $(lsb_release -cs) stable”

** find and remove the previously added bogus entries. One way to find the files is via grep :**

grep -ne ‘^deb.docker.\’ /etc/apt/sources.list{,.d/*.list}