Update content/includes/installation/add-nms-repo.md

Co-authored-by: yar <y82@users.noreply.github.com>

Author: vvnginx

content/includes/installation/add-nms-repo.md

@@ -25,7 +25,7 @@ Add the NGINX Instance Manager repository:
     sudo yum module disable nginx:1.14
     sudo yum module enable nginx:1.20
     ```
-  - **RHEL 9**: If you're installing on RHEL 9 and using the distro's NGINX, run the following commands to use the new version of NGINX (1.20 at the time of this update):
+  - **RHEL 9**: If you're installing NGINX Open Source package from the yum repository on RHEL 9, run the following commands to use the new version of NGINX Open Source (1.20 at the time of this update):
 
     ```bash
     sudo yum install nginx-1.20.*