Starting from 2.2 GA, the APIcast templates for OpenShift (apicast.yml) are configured by default to deploy only a single instance (or "pod/replica") from it.

...
- apiVersion: v1
  kind: DeploymentConfig
  metadata:
    name: "${APICAST_NAME}"
  spec:
    replicas: 1
    selector:
      deploymentconfig: "${APICAST_NAME}"
...

The documentation, however, states:

When the build completes, the UI will refresh and show two instances of APIcast ( 2 pods ) that have been started by OpenShift, as defined in the template.

...

OpenShift will maintain two APIcast instances and monitor the health of both; any unhealthy APIcast instance will automatically be replaced with a new one

—

We need to update the documentation for all the versions affected with something similar to:

When the build completes, the UI will refresh and show one instance of APIcast ( 1 pod ) that have been started by OpenShift, as defined in the template.

...

OpenShift will monitor the pod's health and replace it automatically with a new one if it goes unhealthy.

—

Affected pages and their respective templates:

2.2 GA:

Page: https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.2/html/deployment_options/apicast-openshift#step_2_deploy_apicast_using_the_openshift_template

Template: https://raw.githubusercontent.com/3scale/3scale-amp-openshift-templates/2.2.0.GA/apicast-gateway/apicast.yml

—

2.3 GA:

Page: https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.3/html/deployment_options/apicast-openshift#step_2_deploy_apicast_using_the_openshift_template

Template: https://raw.githubusercontent.com/3scale/3scale-amp-openshift-templates/2.3.0.GA/apicast-gateway/apicast.yml

—

2.4 GA:

Page: https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.4/html/deployment_options/apicast-openshift#step_2_deploy_apicast_using_the_openshift_template

Template: https://raw.githubusercontent.com/3scale/3scale-amp-openshift-templates/2.4.0.GA/apicast-gateway/apicast.yml

—

2.5 GA:

Page: https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.5/html/installing_3scale/apicast-openshift#deploying_apicast_using_the_openshift_template

Template: https://raw.githubusercontent.com/3scale/3scale-amp-openshift-templates/2.5.0.GA/apicast-gateway/apicast.yml

—

SaaS:

Page: https://access.redhat.com/documentation/en-us/red_hat_3scale/2-saas/html/installing_3scale/apicast-openshift#deploying_apicast_using_the_openshift_template

Template: (Same as 2.5 GA)

—

NOTE: The link to the templates (apicast.yml) above are just for information purposes, since they indicate that a single replica from APIcast is deployed starting from 2.2 GA. What needs to be changed is the documentation from the respective versions. The templates for 2.0 GA and 2.1 GA, for reference, contains the 2 replicas:
https://raw.githubusercontent.com/3scale/3scale-amp-openshift-templates/2.0.0.GA-redhat-2/apicast-gateway/apicast.yml
https://raw.githubusercontent.com/3scale/3scale-amp-openshift-templates/2.1.0-GA/apicast-gateway/apicast.yml