docs: remove install/upgrade info using manifests (#3324)

docs/docs/installation/index.md

@@ -8,12 +8,7 @@ Keptn must be installed onto each Kubernetes cluster you want to monitor.
 Additionally, Keptn needs to be enabled on your namespaces.
 This gives you flexibility in how and where you want to use Keptn.
 
-Keptn v0.9.0 and later is installed using [Helm](https://helm.sh/).
-
-> **Note** Earlier releases could also be installed using the manifest.
-> See
-[Upgrade to Helm from a manifest installation](upgrade.md/#upgrade-to-helm-from-a-manifest-installation)
-> if you need to upgrade from a manifest installation.
+Keptn is installed using [Helm](https://helm.sh/).
 
 After you install Keptn, you are ready to
 [Integrate Keptn with your applications](../guides/integrate.md).

docs/docs/installation/upgrade.md

@@ -31,78 +31,3 @@ resources of version `v1alpha3` and `v1alpha4`, you need to
 edit manually created or edited `KeptnApp` resources.
 For further information please refer to the
 [migration section](../migrate/keptnapp/index.md).
-
-## Upgrade to Helm from a manifest installation
-
-> **Warning**
-Upgrade to Helm from a manifest installation can cause loss
-of Keptn custom resources.
-
-Keptn v.0.7.0 and later can be installed with Helm charts;
-Keptn v.0.8.3 can only be installed with Helm.
-If you previously installed Keptn from manifests,
-you can not directly upgrade with Helm but must back up your manifests,
-then reinstall Keptn from a Helm chart and re-apply your manifests.
-
-To start the upgrade process, follow the steps below:
-
-1. To not lose all of your data, we encourage you to do a backup of the manifests,
-which you applied to the cluster (`Deployments`,
-`StatefulSets`, `DaemonSets`, `KeptnApps`,... ).
-After the re-installation of Keptn with Helm, you can re-apply
-these manifests and restart the Keptn deployment process.
-
-1. Completely remove your Keptn installation with the following command sequence:
-
-    ```shell
-    your-keptn-version=<your-keptn-version>
-    kubectl delete -f \
-         https://github.com/keptn/lifecycle-toolkit/releases/download/$your-keptn-version/manifest.yaml
-    ```
-
-1. Use Helm to install a clean version of Keptn:
-
-    ```shell
-    helm repo add keptn https://charts.lifecycle.keptn.sh
-    helm repo update
-    helm upgrade --install keptn keptn/keptn -n keptn-system --create-namespace --wait
-    ```
-
-    For information about  advanced installation options, refer to
-    [Modify Helm configuration options](./index.md).
-
-1. After the installation finishes, restore the manifests from you backup
-
-> **Warning** Please be aware that Keptn applications will start the deployment process from the
-beginning and the system is not guaranteed to return
-to the exact state it was in before re-installation, even if you created the backup correctly.
-
-## Migrate from v0.6.0 to v0.7.0
-
-Keptn Version v0.7.0
-introduces the `metrics-operator`,
-which is now separate from the `lifecycle-operator`.
-Some functionality and behavior has been moved, changed, or renamed.
-
-Specifically, the `KeptnMetricsProvider` CRD replaces
-the now-deprecated `KeptnEvaluationProvider` CRD.
-Consequently, you must manually migrate the existing functionality
-to the `KeptnMetricsProvider` CRD.
-Execute the following external bash script to do this:
-
-```shell
-curl -sL https://raw.githubusercontent.com/keptn/lifecycle-toolkit/main/.github/scripts/keptnevaluationprovider_migrator.sh | bash
-```
-
-This fetches and migrates all `KeptnEvaluationProvider` CRs
-for the cluster at which your kubernetes  context is pointing.
-If you have multiple clusters,
-you must run this command for each one.
-
-This script does the following:
-
-* Fetch all existing `KeptnEvaluationProvider` CRs
-* Migrate each to `KeptnMetricsProvider` CRs
-* Store the migrated manifests in the current working directory
-* Ask the user to apply the created manifests
-  and delete the deprecated `KeptnEvaluationProvider` CRs.