Add Crossplane topic (IaC / Platform Engineering)

[tungbq]

Overview

Tool: Crossplane
Category: IaC / Platform Engineering
Priority: High (per ROADMAP.md)

Crossplane extends Kubernetes to manage cloud infrastructure (databases, networks, storage) as native Kubernetes resources — a key building block of modern platform engineering.

Official docs: https://docs.crossplane.io/

What to add

Follow the existing topic structure — see topics/grafana as a reference:

• topics/crossplane/README.md — sections: What is Crossplane?, Prerequisites, Installation, Basics of Crossplane, Beyond the Basics, More
• topics/crossplane/basics/ — a runnable example (e.g. install Crossplane on a local kind cluster and provision a simple managed resource via a Composition/Provider)
• topics/crossplane/practice/README.md — at least one practice exercise

See CONTRIBUTING.md for the contribution flow.

Why

Listed as High priority in the roadmap's Upcoming Topics table — Kubernetes-native infrastructure management is central to the growing platform-engineering trend this repo already tracks.