docs: tutorial Run Standalone tasks for non-k8s apps (#1947)

docs/content/en/docs/tutorials/tasks-non-k8s-apps.md

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+---
+title: Keptn for Non-Kubernetes Applications
+description: Using Keptn with Non-Kubernetes Applications
+weight: 20
+hidechildren: false # this flag hides all sub-pages in the sidebar-multicard.html
+---
+
+It is possible to trigger Keptn Tasks for workloads and applications that are deployed outside of Kubernetes.
+
+For example, to trigger a load test for an application deployed on a virtual machine.
+
+You will still need to deploy Keptn on a Kubernetes cluster, but this can be a very lightweight, single-node kind cluster.
+Keptn's only job is to trigger on-demand tasks, so resource utilization will be minimal.
+
+## Step 1: Create a KeptnTaskDefinition
+
+When you have Keptn installed, [create a KeptnTaskDefinition](../implementing/tasks/).
+
+A `KeptnTaskDefinition` defines **what** you want to execute.
+
+For example:
+
+```yaml
+apiVersion: lifecycle.keptn.sh/v1alpha3
+kind: KeptnTaskDefinition
+metadata:
+  name: helloworldtask
+spec:
+  retries: 0
+  timeout: 30s
+  container:
+    name: cowsay
+    image: rancher/cowsay:latest
+    args:
+      - 'hello world'
+```
+
+## Step 2: Create a KeptnTask for each run
+
+Each time you want to execute a `KeptnTaskDefinition`, a new (and uniquely named) `KeptnTask` must be created.
+
+In the standard operating mode, when Keptn is managing workloads, the creation of the `KeptnTask` CR is automatic.
+
+Here though, we must create it ourselves.
+
+The `KeptnTask` references the `KeptnTaskDefinition` in the `spec.taskDefinition` field:
+
+```yaml
+apiVersion: lifecycle.keptn.sh/v1alpha3
+kind: KeptnTask
+metadata:
+  name: runhelloworld1
+spec:
+  workload: "my-workload"
+  workloadVersion: "1.0.0"
+  appVersion: "1.0.0"
+  app: "my-app"
+  taskDefinition: helloworldtask
+  context:
+    appName: "my-app"
+    appVersion: "1.0.0"
+    objectType: ""
+    taskType: ""
+    workloadName: "my-workload"
+    workloadVersion: "1.0.0"
+```
+
+Applying this file will cause Keptn to create a Job and a Pod and run the `KeptnTaskDefinition`.
+
+`kubectl get keptntasks` and `kubectl get pods` will show the current status of the jobs.
+
+## Running More KeptnTasks
+
+For subsequent KeptnTask runs, the `KeptnTask` name needs to be unique, update the follow fields:
+
+- `name`
+- `spec.appVersion`
+- `spec.workloadVersion`
+- `spec.context.appVersion`
+- `spec.context.workloadVersion`
+
+For example:
+
+```yaml
+apiVersion: lifecycle.keptn.sh/v1alpha3
+kind: KeptnTask
+metadata:
+  name: runhelloworld2
+spec:
+  workload: "my-workload"
+  workloadVersion: "1.0.1"
+  appVersion: "1.0.1"
+  app: "my-app"
+  taskDefinition: helloworldtask
+  context:
+    appName: "my-app"
+    appVersion: "1.0.1"
+    objectType: ""
+    taskType: ""
+    workloadName: "my-workload"
+    workloadVersion: "1.0.1"
+```