Change yum to dnf

Author: nginx-seanmoloney

site/content/installation-upgrade/installation-oss.md

@@ -301,7 +301,7 @@ Before you install NGINX Agent for the first time on your system, you need to se
     sudo dnf install yum-utils procps
     ```
 
-1. To set up the yum repository for Amazon Linux 2023, create the file named `/etc/yum.repos.d/nginx-agent.repo` with the following contents:
+1. To set up the dnf repository for Amazon Linux 2023, create the file named `/etc/yum.repos.d/nginx-agent.repo` with the following contents:
     ```
     [nginx-agent]
     name=nginx agent repo

site/content/installation-upgrade/installation-plus.md

@@ -376,7 +376,7 @@ Before you install NGINX Agent for the first time on your system, you need to se
     sudo dnf install yum-utils procps ca-certificates
     ```
 
-1. To set up the yum repository for Amazon Linux 2023, create the file named `/etc/yum.repos.d/nginx-agent.repo` with the following contents:
+1. To set up the dnf repository for Amazon Linux 2023, create the file named `/etc/yum.repos.d/nginx-agent.repo` with the following contents:
 
     ```
     [nginx-agent]