Update FAQ.md to add steps for self-hosted provreq (#7092)

* Update FAQ.md to add steps for self-hosted provreq

Adding more observed requirements to use the ProvisioningRequest feature.

* fix typo in provreq flag

* Add clusterrolebinding

Author: rakechill

cluster-autoscaler/FAQ.md

@@ -569,7 +569,40 @@ Provisioning Request (abbr. ProvReq) is a new namespaced Custom Resource that ai
 1. **Cluster Autoscaler Version**: Ensure you are using Cluster Autoscaler version 1.30.1 or later.
 
 2. **Feature Flag**: Enable ProvisioningRequest support by setting the following flag in your Cluster Autoscaler configuration:
---enable-provisioning-reques=true.
+`--enable-provisioning-requests=true`.
+
+3. **Content Type**: This feature requires that the [API content type flag](https://github.com/kubernetes/autoscaler/blob/522c6fcc06c8cf663175ba03549773cc66a02837/cluster-autoscaler/main.go#L114) is set to application/json: `--kube-api-content-type application/json`.
+
+4. **RBAC permissions**: Ensure your cluster-autoscaler pod has the necessary permissions to interact with ProvisioningRequests and PodTemplates:
+```
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: cluster-autoscaler-provisioning
+rules:
+  - apiGroups:
+    - "autoscaling.x-k8s.io"
+    resources:
+    - provisioningrequests
+    - provisioningrequests/status
+    verbs: ["watch", "list", "get", "create", "update", "patch", "delete"]
+  - apiGroups: [""]
+    resources: ["podtemplates"]
+    verbs: ["watch", "list", "get"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: cluster-autoscaler-provisioning-binding
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: cluster-autoscaler-provisioning
+subjects:
+- kind: ServiceAccount
+  name: cluster-autoscaler
+  namespace: kube-system
+```
 
 #### Supported ProvisioningClasses