feat: Clarify subrequest information for F5 WAF (#1445)

This commit updates the Configure NGINX features with F5 WAF document by
clarifying the language around subrequest limitations. The prior
phrasing leads by suggesting they do not work at all.

The new phrasing explains that it works, but has a caveat. Further
language has been clarified in the sentence following it, supporting the
overall structure of the document.

Author: ADubhlaoich

content/waf/configure/nginx-features.md

@@ -14,15 +14,13 @@ nd-product: NAP-WAF
 
 This document shows example of how to modify your NGINX configuration to enable F5 WAF for NGINX features. 
 
-It is intended as a reference for, small self-contained examples of how F5 WAF for NGINX is configured. 
+It is intended as a reference for small, self-contained examples of how F5 WAF for NGINX can be configured. 
 
-Certain features do not work well with NGINX, such as modules requiring _subrequest_ when calling or being called from a scope that contains `app_protect_enable on`.
+F5 WAF for NGINX will secure and inspect client-facing requests, but will not inspect internal subrequests triggered by modules.
 
-Modules requiring the _Range_ header (Such as _Slice_) are also unsupported in a scope which enables F5 WAF for NGINX.
+Modules requiring the _Range_ header (Such as _Slice_) are also unsupported in a scope which enables F5 WAF for NGINX. The examples below work around the contraints of these modules.
 
-The examples below show workarounds for the limitations of these features.
-
-For information on configuring NGINX, you should view the [NGINX documentation]({{< ref "/nginx/" >}}).
+For additional information on configuring NGINX, you should view the [NGINX documentation]({{< ref "/nginx/" >}}).
 
 ## Static location