Docs: Refactor K8s Agent doc

doc/administration/clusters/kas.md

@@ -10,7 +10,7 @@ The Kubernetes Agent Server (KAS) is a GitLab backend service dedicated to
 managing [Kubernetes Agents](../../user/clusters/agent/index.md).
 
 The KAS is already installed and available in GitLab.com under `wss://kas.gitlab.com`.
-See [how to use GitLab.com's KAS](../../user/clusters/agent/index.md#set-up-the-kubernetes-agent-server).
+See [how to use GitLab.com's KAS](../../user/clusters/agent/install/index.md#set-up-the-kubernetes-agent-server).
 This document describes how to install a KAS for GitLab self-managed instances.
 
 ## Installation options

doc/user/application_security/policies/index.md

@@ -159,7 +159,7 @@ at the bottom of the editor.
 
 You can use policy alerts to track your policy's impact. Alerts are only available if you've
 [installed](../../clusters/agent/repository.md)
-and [configured](../../clusters/agent/index.md#create-an-agent-record-in-gitlab)
+and [configured](../../clusters/agent/install/index.md#create-an-agent-record-in-gitlab)
 a Kubernetes Agent for this project.
 
 There are two ways to create policy alerts:

doc/user/clusters/agent/ci_cd_tunnel.md

@@ -21,11 +21,11 @@ Only CI/CD jobs set in the configuration project can access one of the configure
 
 ## Prerequisites
 
-- A running [`kas` instance](index.md#set-up-the-kubernetes-agent-server).
-- A [configuration repository](index.md#define-a-configuration-repository) with an Agent config file
+- A running [`kas` instance](install/index.md#set-up-the-kubernetes-agent-server).
+- A [configuration repository](install/index.md#define-a-configuration-repository) with an Agent config file
   installed (`.gitlab/agents/<agent-name>/config.yaml`).
-- An [Agent record](index.md#create-an-agent-record-in-gitlab).
-- The Agent [installed in the cluster](index.md#install-the-agent-into-the-cluster).
+- An [Agent record](install/index.md#create-an-agent-record-in-gitlab).
+- The Agent [installed in the cluster](install/index.md#install-the-agent-into-the-cluster).
 
 ## Use the CI/CD Tunnel to run Kubernetes commands from GitLab CI/CD