docs: update documentation.

Add short instructions about how to discover and use unstable
Helm charts to the documentation.

Signed-off-by: Krisztian Litkey <[email protected]>

docs/deployment/helm/index.md

@@ -1,5 +1,7 @@
 # Helm
 
+## Stable Helm Charts
+
 All the available charts can be found in [artifacthub.io](https://artifacthub.io/packages/search?ts_query_web=nri&verified_publisher=true&official=true&sort=relevance&page=1).
 
 **NOTE:** NRI-plugins Helm installation has been successfully verified in both local clusters and major Cloud Providers' managed clusters, including:
@@ -19,6 +21,26 @@ All the available charts can be found in [artifacthub.io](https://artifacthub.io
 
 While Ubuntu 20.04/22.04 was used across all three CSP environments, it's worth noting that node images are not limited to Ubuntu 20.04/22.04 only. The majority of widely recognized Linux distributions should be suitable for use.
 
+## Unstable Helm Charts
+
+Helm charts are also published from the main/development branch after each merge.
+These charts reference the latest development images tagged as `unstable` and are
+are stored alongside plugin images in the OCI image registry.
+
+### Discovering Unstable Helm Charts
+
+Unstable charts can be discovered using [skopeo](https://github.com/containers/skopeo).
+For instance, one can list the available charts for the balloons plugin using this
+skopeo command:
+`skopeo list-tags docker://ghcr.io/containers/nri-plugins/nri-resource-policy-balloons`
+
+### Using Unstable Helm Charts
+
+Once discovered, unstable Helm charts can be used like any other. For instance, to use
+the `$X.$Y-unstable` version of the chart to install the development version of the
+balloons plugin one can use this command:
+`helm install --devel -n kube-system test oci://ghcr.io/containers/nri-plugins/nri-resource-policy-balloons --version $X.$Y-unstable --set image.tag=unstable --set image.pullPolicy=Always`
+
 ```{toctree}
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 maxdepth: 2