Add FAQ, closes cetic#47

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,7 +7,7 @@ assignees: ''
 
 ---
 
-<!-- Thanks for filing an issue! Before hitting the button, please answer these questions. It's helpful to search the existing GitHub issues first. It's likely that another user has already reported the issue you're facing, or it's a known issue that we're already aware of 
+<!-- Thanks for filing an issue! Before hitting the button, please answer these questions. It's helpful to search the existing GitHub issues and the [FAQ](/doc/FAQ.md) first. It's likely that another user has already reported the issue you're facing, or it's a known issue that we're already aware of 
 
 Fill in as much of the template below as you can.  If you leave out information, we can't help you as well.
 

README.md

@@ -262,6 +262,7 @@ The following table lists the configurable parameters of the nifi chart and the
 
 Before [filing a bug report](https://github.com/cetic/helm-nifi/issues/new/choose), you may want to:
 
+* check the [FAQ](/doc/FAQ.md)
 * check that [persistent storage](https://kubernetes.io/docs/concepts/storage/persistent-volumes/) is configured on your cluster
 * keep in mind that a first installation may take a significant amount of time on a home internet connection
 * check if a pod is in error: 
@@ -297,7 +298,7 @@ TLS work/inspiration from https://github.com/sushilkm/nifi-chart.git.
 
 Feel free to contribute by making a [pull request](https://github.com/cetic/helm-nifi/pull/new/master).
 
-Please read the official [Contribution Guide](https://github.com/helm/charts/blob/master/CONTRIBUTING.md) from Helm for more information on how you can contribute to this Chart.
+Please read the official [Helm Contribution Guide](https://github.com/helm/charts/blob/master/CONTRIBUTING.md) from Helm for more information on how you can contribute to this Chart.
 
 ## License
 

doc/FAQ.md

@@ -0,0 +1,13 @@
+FAQ - Frequently Asked Questions
+======
+
+Readyness probe fails
+---------------
+
+When encountering errors like `Readiness probe failed: Node not found with CONNECTED state` or `Multi-Attach error for volume "pvc-xxxxxx-xxx-xxx-xxxx-xxxxxxxxx" Volume is already exclusively attached to one node and can't be attached to another`, it means Kubernetes can't provide the pod access to the persistent data it wants. 
+
+When this happens, reach out to your Kubernetes cluster administrators to find and fix the problem manually. 
+
+For more background, see https://blog.mayadata.io/recover-from-volume-multi-attach-error-in-on-prem-kubernetes-clusters
+
+(see https://github.com/cetic/helm-nifi/issues/47#issuecomment-1122702262)