Update README.md

Fixes #2.

README.md

@@ -11,18 +11,26 @@ You will need to have `root` permission on the target system, specifically so yo
 ## Installation
 In a terminal, run the following commands:
 ```
-wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -
-sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
+curl -fsSL https://pkg.jenkins.io/debian-stable/jenkins.io-2023.key | \
+  sudo tee /usr/share/keyrings/jenkins-keyring.asc > /dev/null
+
+echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
+  https://pkg.jenkins.io/debian-stable binary/ | \
+  sudo tee /etc/apt/sources.list.d/jenkins.list > /dev/null
+
 sudo apt-get update -y
+
 sudo apt-get -y install openjdk-11-jdk
+
 sudo apt-get -y install jenkins
+
 sudo cat /var/lib/jenkins/secrets/initialAdminPassword
 ```
 
 ## Using the Initial Admin Password
 Run the following command and copy the output:
 ```
-cat /var/lib/jenkins/secrets/initialAdminPassword
+sudo cat /var/lib/jenkins/secrets/initialAdminPassword
 ```
 
 Open a browser to [localhost:8080](http://localhost:8080) and enter the initial admin password.