add troubleshooting info

Author: paigecalvert

docs/vendor/helm-install-troubleshooting.mdx

@@ -22,4 +22,22 @@ If any top-level charts in the release use the same name, the associated values
 
 Replicated recommends that you use unique names for top-level Helm charts in the same release.
 
-Alternatively, if a release contains charts that must use the same name, convert one or both of the charts into subcharts and use Helm conditions to differentiate them. See [Conditions and Tags](https://helm.sh/docs/chart_best_practices/dependencies/#conditions-and-tags) in the Helm documentation. 
+Alternatively, if a release contains charts that must use the same name, convert one or both of the charts into subcharts and use Helm conditions to differentiate them. See [Conditions and Tags](https://helm.sh/docs/chart_best_practices/dependencies/#conditions-and-tags) in the Helm documentation. 
+
+## Incomplete list of required images in the Helm air gap instructions
+
+### Symptom
+
+The Replicated Enterprise Portal and Download Portal provide instructions for installing with Helm in air-gapped environments. As part of installing with Helm in air-gapped environments, users are instructed to pull all required images for the Helm chart and then push them to their local image registry.
+
+If the list of images in these installation instructions does not include all images required to install and run the chart in an air-gapped environment, then the installation will fail.
+
+### Cause
+
+To create this list of images provided in the Helm air gap installation instructions, the Vendor Portal uses the values in the HelmChart custom resource `builder` key. If the `builder` key was not configured, then the Vendor Portal uses the default values in the Helm chart. However, if the default values do not expose all the images that customers might need to install the chart, then the installation could fail.
+
+### Solution
+
+Configure the `builder` key so that the ouput of `helm template` exposes all the images that might be required to install and run the chart in an air-gapped environment. For more information about how to configure the `builder` key, see [builder](/reference/custom-resource-helmchart-v2#builder) in _HelmChart v2_.
+
+For more information, see [Why you should create `HelmChart` resources for your Helm-only releases](https://community.replicated.com/t/why-you-should-create-helmchart-resources-for-your-helm-only-releases/1539) in the Replicated Community site