add docs for additionalManifest field for RKE2/K3s cluster

docs/reference-guides/cluster-configuration/rancher-server-configuration/k3s-cluster-configuration.md

@@ -231,6 +231,7 @@ spec:
   kubernetesVersion: v1.26.7+k3s1
   localClusterAuthEndpoint: {}
   rkeConfig:
+    additionalManifest: ""
     chartValues: {}
     etcd:
       snapshotRetention: 5
@@ -307,10 +308,37 @@ spec:
 ```
 </details>
 
+### additionalManifest
+
+Specify the addition manifest(s) to be delivered to the control plane nodes. 
+The value is a String, and will be placed at the path `/var/lib/rancher/k3s/server/manifests/rancher/addons.yaml` on target nodes.
+
+Example:
+
+```yaml
+additionalManifest: |-
+  apiVersion: v1
+  kind: Namespace
+  metadata:
+    name: name-xxxx
+```
+
+
+:::note
+
+It is discouraged to provide HelmChartConfig for customizing the system charts via `additionalManifest`,
+it could cause unexpected behavior due to how multiple HelmChartConfig for the same chart being handled.
+
+The recommended approach is to utilize the `chartValues` field which is explained below.
+
+:::
+
 ### chartValues
 
 Specify the values for the system charts installed by K3s.
 
+For more information about how K3s manges packaged components, please refer to [K3s documentation](https://docs.k3s.io/installation/packaged-components).
+
 Example:
 
 ```yaml

docs/reference-guides/cluster-configuration/rancher-server-configuration/rke2-cluster-configuration.md

@@ -280,6 +280,7 @@ spec:
   kubernetesVersion: v1.25.12+rke2r1
   localClusterAuthEndpoint: {}
   rkeConfig:
+    additionalManifest: ""
     chartValues:
       rke2-calico: {}
     etcd:
@@ -337,10 +338,37 @@ spec:
 ```
 </details>
 
+### additionalManifest
+
+Specify the addition manifest(s) to be delivered to the control plane nodes.
+The value is a String, and will be placed at the path `/var/lib/rancher/rke2/server/manifests/rancher/addons.yaml` on target nodes.
+
+Example:
+
+```yaml
+additionalManifest: |-
+  apiVersion: v1
+  kind: Namespace
+  metadata:
+    name: name-xxxx
+```
+
+
+:::note
+
+It is discouraged to provide HelmChartConfig for customizing the system charts via `additionalManifest`,
+it could cause unexpected behavior due to how multiple HelmChartConfig for the same chart being handled.
+
+The recommended approach is to utilize the `chartValues` field which is explained below.
+
+:::
+
 ### chartValues
 
 Specify the values for the system charts installed by RKE2.
 
+For more information about how RKE2 manges packaged components, please refer to [RKE2 documentation](https://docs.rke2.io/helm).
+
 Example:
 
 ```yaml

versioned_docs/version-2.7/reference-guides/cluster-configuration/rancher-server-configuration/k3s-cluster-configuration.md

@@ -231,6 +231,7 @@ spec:
   kubernetesVersion: v1.26.7+k3s1
   localClusterAuthEndpoint: {}
   rkeConfig:
+    additionalManifest: ""
     chartValues: {}
     etcd:
       snapshotRetention: 5
@@ -307,10 +308,37 @@ spec:
 ```
 </details>
 
+### additionalManifest
+
+Specify the addition manifest(s) to be delivered to the control plane nodes.
+The value is a String, and will be placed at the path `/var/lib/rancher/k3s/server/manifests/rancher/addons.yaml` on target nodes.
+
+Example:
+
+```yaml
+additionalManifest: |-
+  apiVersion: v1
+  kind: Namespace
+  metadata:
+    name: name-xxxx
+```
+
+
+:::note
+
+It is discouraged to provide HelmChartConfig for customizing the system charts via `additionalManifest`,
+it could cause unexpected behavior due to how multiple HelmChartConfig for the same chart being handled.
+
+The recommended approach is to utilize the `chartValues` field which is explained below.
+
+:::
+
 ### chartValues
 
 Specify the values for the system charts installed by K3s.
 
+For more information about how K3s manges packaged components, please refer to [K3s documentation](https://docs.k3s.io/installation/packaged-components).
+
 Example:
 
 ```yaml

versioned_docs/version-2.7/reference-guides/cluster-configuration/rancher-server-configuration/rke2-cluster-configuration.md

@@ -280,6 +280,7 @@ spec:
   kubernetesVersion: v1.25.12+rke2r1
   localClusterAuthEndpoint: {}
   rkeConfig:
+    additionalManifest: ""
     chartValues:
       rke2-calico: {}
     etcd:
@@ -337,10 +338,37 @@ spec:
 ```
 </details>
 
+### additionalManifest
+
+Specify the addition manifest(s) to be delivered to the control plane nodes.
+The value is a String, and will be placed at the path `/var/lib/rancher/rke2/server/manifests/rancher/addons.yaml` on target nodes.
+
+Example:
+
+```yaml
+additionalManifest: |-
+  apiVersion: v1
+  kind: Namespace
+  metadata:
+    name: name-xxxx
+```
+
+
+:::note
+
+It is discouraged to provide HelmChartConfig for customizing the system charts via `additionalManifest`,
+it could cause unexpected behavior due to how multiple HelmChartConfig for the same chart being handled.
+
+The recommended approach is to utilize the `chartValues` field which is explained below.
+
+:::
+
 ### chartValues
 
 Specify the values for the system charts installed by RKE2.
 
+For more information about how RKE2 manges packaged components, please refer to [RKE2 documentation](https://docs.rke2.io/helm).
+
 Example:
 
 ```yaml

versioned_docs/version-2.8/reference-guides/cluster-configuration/rancher-server-configuration/k3s-cluster-configuration.md

@@ -231,6 +231,7 @@ spec:
   kubernetesVersion: v1.26.7+k3s1
   localClusterAuthEndpoint: {}
   rkeConfig:
+    additionalManifest: ""
     chartValues: {}
     etcd:
       snapshotRetention: 5
@@ -307,10 +308,37 @@ spec:
 ```
 </details>
 
+### additionalManifest
+
+Specify the addition manifest(s) to be delivered to the control plane nodes.
+The value is a String, and will be placed at the path `/var/lib/rancher/k3s/server/manifests/rancher/addons.yaml` on target nodes.
+
+Example:
+
+```yaml
+additionalManifest: |-
+  apiVersion: v1
+  kind: Namespace
+  metadata:
+    name: name-xxxx
+```
+
+
+:::note
+
+It is discouraged to provide HelmChartConfig for customizing the system charts via `additionalManifest`,
+it could cause unexpected behavior due to how multiple HelmChartConfig for the same chart being handled.
+
+The recommended approach is to utilize the `chartValues` field which is explained below.
+
+:::
+
 ### chartValues
 
 Specify the values for the system charts installed by K3s.
 
+For more information about how K3s manges packaged components, please refer to [K3s documentation](https://docs.k3s.io/installation/packaged-components).
+
 Example:
 
 ```yaml

versioned_docs/version-2.8/reference-guides/cluster-configuration/rancher-server-configuration/rke2-cluster-configuration.md

@@ -280,6 +280,7 @@ spec:
   kubernetesVersion: v1.25.12+rke2r1
   localClusterAuthEndpoint: {}
   rkeConfig:
+    additionalManifest: ""
     chartValues:
       rke2-calico: {}
     etcd:
@@ -337,10 +338,37 @@ spec:
 ```
 </details>
 
+### additionalManifest
+
+Specify the addition manifest(s) to be delivered to the control plane nodes.
+The value is a String, and will be placed at the path `/var/lib/rancher/rke2/server/manifests/rancher/addons.yaml` on target nodes.
+
+Example:
+
+```yaml
+additionalManifest: |-
+  apiVersion: v1
+  kind: Namespace
+  metadata:
+    name: name-xxxx
+```
+
+
+:::note
+
+It is discouraged to provide HelmChartConfig for customizing the system charts via `additionalManifest`,
+it could cause unexpected behavior due to how multiple HelmChartConfig for the same chart being handled.
+
+The recommended approach is to utilize the `chartValues` field which is explained below.
+
+:::
+
 ### chartValues
 
 Specify the values for the system charts installed by RKE2.
 
+For more information about how RKE2 manges packaged components, please refer to [RKE2 documentation](https://docs.rke2.io/helm).
+
 Example:
 
 ```yaml