nixos/k3s: add autoDeployCharts option

The `autoDeployCharts` option further improves the auto deploying
capabilities of the k3s module by allowing to deploy and configure Helm charts
that are then instaled via the k3s Helm controller. Although this was
also previously possible by using auto deploying manifests, it required
some knowledge of the k3s Helm controller and led to a lot of
boilerplate code.

nixos/doc/manual/release-notes/rl-2505.section.md

@@ -361,6 +361,8 @@
 - The paperless module now has an option for regular automatic export of
   documents data using the integrated document exporter.
 
+- `services.k3s` now provides the [](#opt-services.k3s.autoDeployCharts) option that allows to automatically deploy Helm charts via the k3s Helm controller.
+
 - Caddy can now be built with plugins by using `caddy.withPlugins`, a `passthru` function that accepts an attribute set as a parameter. The `plugins` argument represents a list of Caddy plugins, with each Caddy plugin being a versioned module. The `hash` argument represents the `vendorHash` of the resulting Caddy source code with the plugins added.
 
   Example: