Add documentation for multiline expansion

[yissachar]

No description provided.

[justinsb]

I'm wondering if this is actually a bug in kexpand... i.e. are we painting ourselves into a corner by explicitly supporting this.

I like the idea of making the decision through docs :-)

I opened kubernetes/kubernetes#36750 to get some clarity on whether this is possible in the official syntax, and hopefully whether anyone is working on this!

Given some of the limitations, I think I would prefer to use some sort of combination logic (like kubectl apply does - they call it a smart merge or similar), rather than rely on correct indentation. But let's see what kubernetes/kubernetes#36750 flushes out.

[yissachar]

Yeah, this was a kind of hacky solution to a real problem I had, but I figured I would document it so that others in the same situation could use it as well. To be honest, I'm not sure that this is considered in scope for templates; it might be that when you have these sorts of requirements it's time to move to Helm, which has much more robust template support.