Update content/includes/waf/install-build-image.md

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

Author: dkleinF5

content/includes/waf/install-build-image.md

@@ -27,7 +27,7 @@ podman build --no-cache --secret id=nginx-crt,src=nginx-repo.crt --secret id=ngi
 ```
 
 #### Building an image with NGINX Open Source
-To build an image for NGINX Open Source, use the following command that are not RHEL-based, replacing `<your-image-name>` as appropriate:
+To build an image for NGINX Open Source, use the following command that is not RHEL-based, replacing `<your-image-name>` as appropriate:
 
 ```shell
 sudo docker build --no-cache --platform linux/amd64 --secret id=nginx-crt,src=nginx-repo.crt --secret id=nginx-key,src=nginx-repo.key -t <your-image-name> .