Update PGO upgrade docs

When upgrading to v5.4, Kustomize installations will require
deletion of the pgo-upgrade deployment.

Issue: [sc-16349]

Author: tony-landreth

docs/content/upgrade/helm.md

@@ -5,7 +5,7 @@ draft: false
 weight: 70
 ---
 
-Once PGO v5.0.x has been installed with Helm, it can then be upgraded using the `helm upgrade` command.
+Once PGO v5 has been installed with Helm, it can then be upgraded using the `helm upgrade` command.
 However, before running the `upgrade` command, any CustomResourceDefinitions (CRDs) must first be
 manually updated (this is specifically due to a [design decision in Helm v3][helm-crd-limits],
 in which any CRDs in the Helm chart are only applied when using the `helm install` command).
@@ -33,3 +33,5 @@ Then, perform the upgrade using Helm:
 ```shell
 helm upgrade <name> -n <namespace> helm/install
 ```
+PGO versions earlier than v5.4.0 include a pgo-upgrade deployment. When upgrading to v5.4.x, users
+should expect the pgo-upgrade deployment to be deleted automatically.

docs/content/upgrade/kustomize.md

@@ -5,6 +5,21 @@ draft: false
 weight: 50
 ---
 
+## Upgrading to v5.4.0 from v5.3.x
+
+Apply the new version of the Kubernetes installer:
+
+```bash
+kubectl apply --server-side -k kustomize/install/default
+```
+
+PGO versions from 5.1.x through 5.3.x include a pgo-upgrade deployment, which
+is no longer needed after upgrading to v5.4.x. Delete the deployment:
+
+```bash
+kubectl delete deployment pgo-upgrade
+```
+
 ## Upgrading from PGO v5.0.0 Using Kustomize
 
 Starting with PGO v5.0.1, both the Deployment and ServiceAccount created when installing PGO via