an error occurs when downloading the package lists from the repository https.
it is connected with distrust of the certificate on the remote server.
E: The repository 'https://apt.dockerproject.org/repo ubuntu-xenial 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.
an error occurs when downloading the package lists from the repository https. it is connected with distrust of the certificate on the remote server.