add helm charts

backing-services/istiod/README.md

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+# Istiod Helm Chart
+
+This chart installs an Istiod deployment.
+
+## Setup Repo Info
+
+```console
+helm repo add istio https://istio-release.storage.googleapis.com/charts
+helm repo update
+```
+
+_See [helm repo](https://helm.sh/docs/helm/helm_repo/) for command documentation._
+
+## Installing the Chart
+
+Before installing, ensure CRDs are installed in the cluster (from the `istio/base` chart).
+
+To install the chart with the release name `istiod`:
+
+```console
+kubectl create namespace istio-system
+helm install istiod istio/istiod --namespace istio-system
+```
+
+## Uninstalling the Chart
+
+To uninstall/delete the `istiod` deployment:
+
+```console
+helm delete istiod --namespace istio-system
+```
+
+## Configuration
+
+To view support configuration options and documentation, run:
+
+```console
+helm show values istio/istiod
+```
+
+### Profiles
+
+Istio Helm charts have a concept of a `profile`, which is a bundled collection of value presets.
+These can be set with `--set profile=<profile>`.
+For example, the `demo` profile offers a preset configuration to try out Istio in a test environment, with additional features enabled and lowered resource requirements.
+
+For consistency, the same profiles are used across each chart, even if they do not impact a given chart.
+
+Explicitly set values have highest priority, then profile settings, then chart defaults.
+
+As an implementation detail of profiles, the default values for the chart are all nested under `defaults`.
+When configuring the chart, you should not include this.
+That is, `--set some.field=true` should be passed, not `--set defaults.some.field=true`.
+
+### Examples
+
+#### Configuring mesh configuration settings
+
+Any [Mesh Config](https://istio.io/latest/docs/reference/config/istio.mesh.v1alpha1/) options can be configured like below:
+
+```yaml
+meshConfig:
+  accessLogFile: /dev/stdout
+```
+
+#### Revisions
+
+Control plane revisions allow deploying multiple versions of the control plane in the same cluster.
+This allows safe [canary upgrades](https://istio.io/latest/docs/setup/upgrade/canary/)
+
+```yaml
+revision: my-revision-name
+```