Add note about installation on kubernetes to docs (#13469)

Co-authored-by: zeripath <art27@cantab.net>

docs/content/doc/installation/on-kubernetes.en-us.md

@@ -0,0 +1,27 @@
+---
+date: "2020-03-19T19:27:00+02:00"
+title: "Install on Kubernetes"
+slug: "install-on-kubernetes"
+weight: 10
+toc: true
+draft: false
+menu:
+  sidebar:
+    parent: "installation"
+    name: "Kubernetes"
+    weight: 50
+    identifier: "install-on-kubernetes"
+---
+
+# Installation with Helm (on Kubernetes)
+
+Gitea provides a Helm Chart to allow for installation on kubernetes.
+
+A non-customized install can be done with:
+
+```
+helm repo add gitea-charts https://dl.gitea.io/charts/
+helm install gitea gitea-charts/gitea
+```
+
+If you would like to customize your install, which includes kubernetes ingress, please refer to the complete [Gitea helm chart configuration details](https://gitea.com/gitea/helm-chart/)