doc/faq: create common QA to be used as helper (#16)

* doc/faq: create common QA to be sed as helper

* Update docs/FAQ.md

* docs(user)/faq; nits to keep the text more clear

docs/FAQ.md

@@ -0,0 +1,27 @@
+# FAQ for OpenShift Provider Certification Tool
+
+**Q: What is the OpenShift Provider Certification Tool (OPCT) ?**
+
+OPCT was designed to validate the custom OpenShift installations in non-integrated providers (a.k.a [agnostic installation](https://docs.openshift.com/container-platform/4.11/installing/installing_platform_agnostic/installing-platform-agnostic.html) with `platform.none:{}` option for `install-config.yaml`), **running existing suite of e2e tests** from Kubernetes and OpenShift ecosystem.
+
+OPCT was build on top of [Sonobuoy](https://sonobuoy.io/) and [openshift-tests](https://github.com/openshift/origin#end-to-end-e2e-and-extended-tests) utilities. The `openshift-tests` tool
+is used to run conformance test suites across the CI Jobs, and also the [Kubernetes Certification Program](https://www.cncf.io/certification/software-conformance/). The `sonobuoy` tool is used to automate the certification environment, running many custom plugins implemented to meet the requirements of OpenShift Provider Certification Program.
+
+**Q: What was OPCT not created for?**
+
+It's not created to:
+* replace OpenShift CI tests/clusters tooling
+* implement OpenShift's component-specific e2e tests
+* implement Provider's specific e2e test
+
+**Q: Is it possible to write custom e2e tests from my custom component?**
+
+Possibly yes, but it's not recommended and not supported by OPCT. The
+OPCT was designed to implement the requirements of VSCP/OpenShift Provider Certification Program. The e2e tests
+written as a plugin on OPCT are specific for the certification, or evaluate
+specific install requirements on OpenShift cluster installed on external/non-supported platforms.
+
+You have those options to implement e2e tests that should be tested on OpenShift installation:
+
+* add the tests on the [openshift-tests utility](https://github.com/openshift/origin#end-to-end-e2e-and-extended-tests)
+* if you would like to create a Sonobuoy plugin to keep compatibility with the existing certification tools, you can start looking at the [example repository](https://github.com/vmware-tanzu/sonobuoy-plugins/tree/main/examples/e2e-skeleton)