Update instructions for upgrading NGINX Agent (#648)

* Update instructions for upgrading NGINX Agent

* PR feedback

Co-authored-by: Jon Torre <[email protected]>

* PR feedback

Co-authored-by: Jon Torre <[email protected]>

* PR feedback

Co-authored-by: Jon Torre <[email protected]>

---------

Co-authored-by: Jon Torre <[email protected]>

Author: nginx-seanmoloney

content/agent/installation-upgrade/upgrade.md

@@ -12,9 +12,7 @@ type:
 
 Learn how to upgrade NGINX Agent.
 
-## Upgrade NGINX Agent from version v2.31.0 or greater
-
-{{< note >}} Starting from version v2.31.0, NGINX Agent will automatically restart itself during an upgrade. {{< /note >}}
+## Upgrade NGINX Agent
 
 To upgrade NGINX Agent, follow these steps:
 
@@ -41,43 +39,48 @@ To upgrade NGINX Agent, follow these steps:
         sudo apt-get install -y --only-upgrade nginx-agent -o Dpkg::Options::="--force-confold"
         ```
 
+## Upgrade NGINX Agent to a Specific Version 
 
+To upgrade NGINX Agent to a specific **v2.x version**, follow these steps: 
 
-## Upgrade NGINX Agent from a version less than v2.31.0
-
-To upgrade NGINX Agent, take the following steps:
+#### Steps to Upgrade: 
 
-1. Open an SSH connection to the server where you’ve installed NGINX Agent and log in.
+1. Open an SSH connection to the server running  NGINX Agent and log in.
 
-1. Make a backup copy of the following locations to ensure that you can successfully recover if the upgrade has issues:
+1. Back up the following files and directories to ensure you can restore the environment in case of issues during the upgrade: 
 
     - `/etc/nginx-agent`
-    - `config_dirs` values for any configuration specified in `/etc/nginx-agent/nginx-agent.conf`
-
-1. Stop NGINX Agent:
+    - Any `config_dirs` directory specified in `/etc/nginx-agent/nginx-agent.conf`.
 
-    ```shell
-    sudo systemctl stop nginx-agent
-    ```
-
-1. Install the updated version of NGINX Agent:
-
-    - CentOS, RHEL, RPM-Based
+1. Perform the version-controlled upgrade. 
 
+   - Debian, Ubuntu, Deb-Based
+        
         ```shell
-        sudo yum -y makecache
-        sudo yum update -y nginx-agent
+        sudo apt-get update
+        sudo apt-get install -y nginx-agent=<specific-version> -o Dpkg::Options::="--force-confold"
         ```
-
-    - Debian, Ubuntu, Deb-Based
-
+        
+        Example (to upgrade to version 2.41.1~noble): 
+        
         ```shell
-        sudo apt-get update
-        sudo apt-get install -y --only-upgrade nginx-agent -o Dpkg::Options::="--force-confold"
+        sudo apt-get install -y nginx-agent=2.41.1~noble -o Dpkg::Options::="--force-confold"
         ```
 
-1. Start NGINX Agent:
+    - CentOS, RHEL, RPM-Based        
+       
+        ```shell
+        sudo yum install -y nginx-agent-<specific-version>
+        ```
+        
+        Example (to upgrade to version `2.41.1`): 
+    
+        ```shell
+        sudo yum install -y nginx-agent-2.41.1
+        ```
 
+1. Verify the installed version:    
+    
     ```shell
-    sudo systemctl start nginx-agent
+    sudo nginx-agent --version
     ```