In configuring the che installation, describe a generic way to configure the CheCluster Custom Resource

In https://www.eclipse.org/che/docs/che-7/installation-guide/configuring-the-che-installation/ we state: "To learn how to modify the CheCluster Custom Resource, see the chosen installation procedure."

Instead of bouncing back to the installation method, we should include procedures describing all relevant scenarios to configure the CheCluster Custom Resource.

• Using the OpenShift 4 Web UI
• Using the prod-cli (chectl/crwctl)
• Using the orch-cli (kubectl/oc)

For both CLI scenarios, document only how to create a patch YAML and apply it. Don't describe the one liner scenario where the configuration item is hidden in the command line as a JSON string.

Later on, we will be able to simplify stories implying configuration of the CR into 2 steps procedures:

1. Define the parameters to use as placeholders
2. Apply the relevant procedure to configure the Checluster Custom Resource + link to https://www.eclipse.org/che/docs/che-7/installation-guide/configuring-the-che-installation/

Here is a basic outline, that need refinement and tests:

Configuring the CheCluster Custom Resource during installation using the OpenShift 4 Web UI

Prerequisites

• Define placeholders: the configuration items to change.

Procedure

1. Execute https://www.eclipse.org/che/docs/che-7/installation-guide/installing-che-on-openshift-4-using-operatorhub/#creating-an-instance-of-the-che-operator_che but in step 4: apply the desired values of the CR.

Configuring the CheCluster Custom Resource of a running {prod-short} instance using the OpenShift 4 Web UI

Prerequisites

• Define placeholders: the configuration items to change.

Procedure

1. In the OpenShift Web UI, navigate to ... then .. then ... until you reach the edit CheCluster Custom Resource.
2. Edit the CheCluster Custom Resource, and apply. 

Configuring the CheCluster Custom Resource using {prod-cli}

Prerequisites

• Define _<placeholder>_: the configuration items to change.

Procedure

1. Create a YAML file che-operator-cr-patch.yaml containing the subset of the CheCluster Custom Resource necessary to perform the desired modification.

   spec:
     __<placeholder>__
   

1. Apply the patch YAML.

    
   $ {prod-cli} server:deploy --che-operator-cr-patch-yaml=che-operator-cr-patch.yaml
   

(NB: same procedure to install and configuring a running instance)

NB: for inspiration, examples of procedures already describing how to patch the CR:

• https://www.eclipse.org/che/docs/che-7/installation-guide/configuring-routes/
• See https://github.com/che-incubator/chectl doc:  {{--che-operator-cr-patch-yaml=che-operator-cr-patch-yaml
  Path to a yaml file that overrides the default values in CheCluster CR used by the operator. This parameter is used
  only when the installer is the 'operator' or the 'olm'.}}

Configuring the CheCluster Custom Resource using {orch-cli}

.Prerequisites

• Define _<placeholder>_: the configuration items to change.

.Procedure

1. Create a YAML file checluster-patch.yaml containing the subset of the CheCluster Custom Resource necessary to perform the desired modification.

   apiVersion: org.eclipse.che/v1
    kind: CheCluster
    metadata:
    name: eclipse-che
    spec:
    __<placeholder>__
   

1. Apply the patch YAML.

    $ {orch-cli} apply -f _checluster-patch.yaml_
   

   (NB: configuring a running instance only)

NB: for inspiration, examples of procedures already describing how to patch the CR:

• https://www.eclipse.org/che/docs/che-7/installation-guide/configuring-workspace-exposure-strategies/