docs: Add a description for the OpaCluster CRD #243

Job	Run time
Detect relevant changed files	4s
Build/Publish amd64 Image	7m 39s
Run cargo-udeps	2m 13s
Build/Publish arm64 Image	5m 58s
Publish/Sign 0.0.0-pr843 Index	29s
Package/Publish 0.0.0-pr843 Helm Chart	27s
Run OpenShift Preflight Check for 0.0.0-pr843-amd64	19s
Run OpenShift Preflight Check for 0.0.0-pr843-arm64	18s
Failure Notification	-1s
Finished Build and Publish	2s
	17m 28s

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