Add NGINX Agent v3.0 SELinux configuration guide

Author: dhurley

content/agent/how-to/how-to-configure-selinux.md

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+---
+title: Configure SELinux
+weight: 600
+---
+
+## Overview
+
+You can use the optional SELinux policy module included in the package to secure F5 NGINX Agent operations with flexible, mandatory access control that follows the principle of least privilege.
+
+{{< important >}}The SELinux policy module is optional. It is not loaded automatically during installation, even on SELinux-enabled systems. You must manually load the policy module using the steps below.{{< /important >}}
+
+---
+
+## Before you begin
+
+Take these preparatory steps before configuring SELinux:
+
+1. Enable SELinux on your system.
+2. Install the tools `load_policy`, `semodule`, and `restorecon`.
+3. [Install NGINX Agent]({{< rel "/agent/install-upgrade/install.md" >}}) with SELinux module files in place.
+
+{{< important >}}SELinux can use `permissive` mode, where policy violations are logged instead of enforced. Verify which mode your configuration uses.{{< /important >}}
+
+---
+
+## Enable SELinux for NGINX Agent {#selinux-agent}
+
+The following SELinux files are added when you install the NGINX Agent package:
+
+- `/usr/share/selinux/packages/nginx_agent.pp` - loadable binary policy module
+- `/usr/share/selinux/devel/include/contrib/nginx_agent.if` - interface definitions file
+- `/usr/share/man/man8/nginx_agent_selinux.8.gz` - policy man page
+
+To load the NGINX Agent policy, run:
+
+{{< include "installation/agent-selinux.md" >}}
+
+{{<see-also>}}For more information, see [Using NGINX and NGINX Plus with SELinux](https://www.nginx.com/blog/using-nginx-plus-with-selinux/).{{</see-also>}}
+
+---
+
+## Recommended Resources
+
+- <https://man7.org/linux/man-pages/man8/selinux.8.html>
+- <https://www.redhat.com/en/topics/linux/what-is-selinux>
+- <https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/using_selinux>
+- <https://wiki.centos.org/HowTos/SELinux>
+- <https://wiki.gentoo.org/wiki/SELinux>
+- <https://opensource.com/business/13/11/selinux-policy-guide>
+- <https://www.nginx.com/blog/using-nginx-plus-with-selinux/>