Move PSP into Security concepts section

The logical navigation definitely works better if Pod Security admission
and PodSecurityPolicy are pages in the same section. Make It So.

Co-authored-by: Rey Lejano <rlejano@gmail.com>

content/en/blog/_posts/2020-11-18-cloud-native-security-for-your-cluster/index.md

@@ -18,7 +18,7 @@ The paper attempts to _not_ focus on any specific [cloud native project](https:/
 
 ## Kubernetes native security controls
 When using Kubernetes as a workload orchestrator, some of the security controls this version of the whitepaper recommends are:
-* [Pod Security Policies](/docs/concepts/policy/pod-security-policy/): Implement a single source of truth for “least privilege” workloads across the entire cluster
+* [Pod Security Policies](/docs/concepts/security/pod-security-policy/): Implement a single source of truth for “least privilege” workloads across the entire cluster
 * [Resource requests and limits](/docs/concepts/configuration/manage-resources-containers/#requests-and-limits): Apply requests (soft constraint) and limits (hard constraint) for shared resources such as memory and CPU
 * [Audit log analysis](/docs/tasks/debug-application-cluster/audit/): Enable Kubernetes API auditing and filtering for security relevant events
 * [Control plane authentication and certificate root of trust](/docs/concepts/architecture/control-plane-node-communication/): Enable mutual TLS authentication with a trusted CA for communication within the cluster

content/en/blog/_posts/2021-04-06-PodSecurityPolicy-Past-Present-and-Future.md

@@ -21,7 +21,7 @@ Until then, PSP is still PSP. There will be at least a year during which the new
 
 ## What is PodSecurityPolicy?
 
-[PodSecurityPolicy](/docs/concepts/policy/pod-security-policy/) is a built-in [admission controller](/blog/2019/03/21/a-guide-to-kubernetes-admission-controllers/) that allows a cluster administrator to control security-sensitive aspects of the Pod specification. 
+[PodSecurityPolicy](/docs/concepts/security/pod-security-policy/) is a built-in [admission controller](/blog/2019/03/21/a-guide-to-kubernetes-admission-controllers/) that allows a cluster administrator to control security-sensitive aspects of the Pod specification. 
 
 First, one or more PodSecurityPolicy resources are created in a cluster to define the requirements Pods must meet. Then, RBAC rules are created to control which PodSecurityPolicy applies to a given pod. If a pod meets the requirements of its PSP, it will be admitted to the cluster as usual. In some cases, PSP can also modify Pod fields, effectively creating new defaults for those fields. If a Pod does not meet the PSP requirements, it is rejected, and cannot run. 
 

content/en/blog/_posts/2021-10-05-nsa-cisa-hardening.md

@@ -175,7 +175,7 @@ require internet access to update the vulnerability database.
 
 ### Pod Security Policies
 
-Since Kubernetes v1.21, the [PodSecurityPolicy](/docs/concepts/policy/pod-security-policy/) 
+Since Kubernetes v1.21, the [PodSecurityPolicy](/docs/concepts/security/pod-security-policy/) 
 API and related features are [deprecated](/blog/2021/04/06/podsecuritypolicy-deprecation-past-present-and-future/),
 but some of the guidance in this section will still apply for the next few years, until cluster operators
 upgrade their clusters to newer Kubernetes versions.

content/en/blog/_posts/2021-11-09-non-root-containers-and-devices.md

@@ -18,7 +18,7 @@ One of the key security principles for running containers in Kubernetes is the
 principle of least privilege. The Pod/container `securityContext` specifies the config
 options to set, e.g., Linux capabilities, MAC policies, and user/group ID values to achieve this.
 
-Furthermore, the cluster admins are supported with tools like [PodSecurityPolicy](/docs/concepts/policy/pod-security-policy/) (deprecated) or
+Furthermore, the cluster admins are supported with tools like [PodSecurityPolicy](/docs/concepts/security/pod-security-policy/) (deprecated) or
 [Pod Security Admission](/docs/concepts/security/pod-security-admission/) (alpha) to enforce the desired security settings for pods that are being deployed in
 the cluster. These settings could, for instance, require that containers must be `runAsNonRoot` or
 that they are forbidden from running with root's group ID in `runAsGroup` or `supplementalGroups`.

content/en/blog/_posts/2021-12-09-pod-security-admission-beta.md

@@ -9,7 +9,7 @@ slug: pod-security-admission-beta
 
 With the release of Kubernetes v1.23, [Pod Security admission](/docs/concepts/security/pod-security-admission/) has now entered beta. Pod Security is a [built-in](/docs/reference/access-authn-authz/admission-controllers/) admission controller that evaluates pod specifications against a predefined set of [Pod Security Standards](/docs/concepts/security/pod-security-standards/) and determines whether to `admit` or `deny` the pod from running.
 
-Pod Security is the successor to [PodSecurityPolicy](/docs/concepts/policy/pod-security-policy/) which was deprecated in the v1.21 release, and will be removed in Kubernetes v1.25. In this article, we cover the key concepts of Pod Security along with how to use it. We hope that cluster administrators and developers alike will use this new mechanism to enforce secure defaults for their workloads.
+Pod Security is the successor to [PodSecurityPolicy](/docs/concepts/security/pod-security-policy/) which was deprecated in the v1.21 release, and will be removed in Kubernetes v1.25. In this article, we cover the key concepts of Pod Security along with how to use it. We hope that cluster administrators and developers alike will use this new mechanism to enforce secure defaults for their workloads.
 
 ## Why Pod Security