Update container-runtimes.md (#18608)

for debian install of docker, also install gnupg2 for apt-key add to work

content/en/docs/setup/production-environment/container-runtimes.md

@@ -75,7 +75,7 @@ Use the following commands to install Docker on your system:
 ## Set up the repository:
 ### Install packages to allow apt to use a repository over HTTPS
 apt-get update && apt-get install -y \
-  apt-transport-https ca-certificates curl software-properties-common
+  apt-transport-https ca-certificates curl software-properties-common gnupg2
 
 ### Add Docker’s official GPG key
 curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -