Tutorials: Update docker install to the latest instructions on the official website

doc/NR_SA_Tutorial_OAI_CN5G.md

@@ -33,11 +33,12 @@ Minimum hardware requirements:
 sudo apt install -y git net-tools putty
 
 # https://docs.docker.com/engine/install/ubuntu/
-sudo apt install -y ca-certificates curl gnupg
+sudo apt update
+sudo apt install -y ca-certificates curl
 sudo install -m 0755 -d /etc/apt/keyrings
-curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
-sudo chmod a+r /etc/apt/keyrings/docker.gpg
-echo "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
+sudo chmod a+r /etc/apt/keyrings/docker.asc
+echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
 sudo apt update
 sudo apt install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin