Document controller health probes

[GrigoriyMikhalkin]

Was mentioned in comments to #419, that it's not quite clear how to set health probes for controller.

Would be nice to add minimal example of manager with health/readiness checks.

P.S. I would gladly do that

[alexeldeib]

I really like the examples provided by controller runtime, for example the package level one: https://github.com/kubernetes-sigs/controller-runtime/blob/master/example_test.go

and the webhook specific one: https://github.com/kubernetes-sigs/controller-runtime/blob/master/pkg/webhook/example_test.go

perhaps we could had a runnable main.go example with healthz?

[alexeldeib]

If that's already what you meant, i'd go for it!

[GrigoriyMikhalkin]

@alexeldeib Was thinking more about adding example to https://github.com/kubernetes-sigs/controller-runtime/blob/master/pkg/manager/example_test.go (please check PR).

But adding runnable example(in addition), also a good idea. Maybe we can add health probes to examples in https://github.com/kubernetes-sigs/controller-runtime/tree/master/examples, what you think?

[vincepri]

/kind documentation
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[LeoLiuYan]

Maybe I can work for it?

[LeoLiuYan]

/assign

[LeoLiuYan]

/assign