ACA-2437: added a new CI file (#273)

* added a new CI file, migrated testing information to it, and enhanced the README

* simplify CI.md to match kubernetes.core format

* rewrite CI file to reflect zuul and prow testing

CI.md

@@ -0,0 +1,64 @@
+# Continuous Integration (CI)
+
+This collection uses two CI systems: **Zuul** for PR validation checks and **Prow** for integration testing.
+
+## Zuul - PR Validation
+
+Zuul runs automated tests on every pull request. The Zuul configuration for this collection is defined in the [ansible/ansible-zuul-jobs](https://github.com/ansible/ansible-zuul-jobs/blob/main/zuul.d/project-templates.yaml) repository under the `ansible-collections-community-okd` template.
+
+### Jobs Run by Zuul
+
+The following jobs run in the `third-party-check` pipeline on every PR:
+
+| Job | Description |
+| --- | ----------- |
+| `build-ansible-collection` | Builds the collection tarball |
+| `ansible-galaxy-importer` | Validates collection structure for Galaxy (non-voting) |
+| `ansible-tox-linters` | Runs `black`, `flake8`, and `ansible-lint` via `tox -e linters` (see [tox.ini](tox.ini)) |
+| `ansible-test-units-community-okd-python39` | Executes unit tests with Python 3.9 |
+
+**Upstream Sanity Tests:**
+- `ansible-test-sanity-docker-devel`
+- `ansible-test-sanity-docker-milestone`
+- `ansible-test-sanity-docker-stable-2.16`
+- `ansible-test-sanity-docker-stable-2.17`
+- `ansible-test-sanity-docker-stable-2.18`
+
+**Downstream Sanity Tests** (test the `redhat.openshift` variant):
+- `ansible-test-sanity-okd-downstream-devel`
+- `ansible-test-sanity-okd-downstream-milestone`
+- `ansible-test-sanity-okd-downstream-stable-2.16`
+- `ansible-test-sanity-okd-downstream-stable-2.17`
+- `ansible-test-sanity-okd-downstream-stable-2.18`
+
+## OpenShift Prow - Integration Testing
+
+Integration tests for community.okd are executed via [OpenShift Prow](https://github.com/kubernetes/test-infra/blob/master/prow/README.md), OpenShift's CI/CD system for testing against live clusters.
+
+### Prow Configuration
+
+The Prow configuration for this collection is maintained in the [openshift/release](https://github.com/openshift/release) repository at `ci-operator/config/openshift/community.okd/openshift-community.okd-main.yaml`.
+
+### Integration Test Workflow
+
+The integration test workflow follows these steps:
+
+1. **Prow builds the test runner image** defined in [ci/Dockerfile](ci/Dockerfile)
+   - Based on `registry.access.redhat.com/ubi9/ubi`
+   - Includes Python 3.12, ansible-core, molecule, kubernetes client, and OKD CLI tools
+
+2. **Prow executes `make test-integration-incluster`**
+   - This runs [ci/incluster_integration.sh](ci/incluster_integration.sh)
+
+3. **The script spawns a Kubernetes Job** that runs `make test-integration` using the previously built image
+   - Job runs with cluster-admin permissions
+   - 30-minute timeout
+   - Backoff limit of 2 retries
+
+4. **`make test-integration` runs both upstream and downstream tests:**
+   - **Upstream tests** (`upstream-test-integration`): Runs molecule tests for `community.okd` collection
+   - **Downstream tests** (`downstream-test-integration`): Runs `ci/downstream.sh -i` to convert the collection to `redhat.openshift` and test the downstream variant
+
+### Test Framework
+
+Integration tests use the Molecule framework and require a live OpenShift or Kubernetes cluster (>=1.24). Tests are located in the `molecule/default/` directory and cover check mode, creation, idempotency, modification, and deletion scenarios.