[DOKS-CI-CD] Extend main tutorial to cover additional topics

[v-ctiutiu]

Additional topics to complement the main DOKS-CI-CD blueprint:

1. Simplifying creation and management of Tekton pipelines definitions via other tools, such as Jsonnet (working with too much YAML content can become a pain in the future).
2. Running tests as part of Tekton pipelines (practical example being PRs validation).
3. Dealing with application release and versioning using Tekton pipelines.
4. Releasing and dealing with various environments, such as DEV, QA, STAGING, PROD.
5. Using ArgoCD to bootstrap and sync all tutorial components (including the tooling, such as Knative, Tekton, etc.)