Kubernetes walk-through outdated

[cueckoo]

Originally opened by @trebe in cuelang/cue#31

Thanks for the nice walkthrough, that shows some of the great power of Cue :-)
Parts of it refers to previous versions of Cue:

cue eval ./... > snapshot2 doesn't fail as indicated, since now eval can output non-atomic string

Under "1 is the default", 1 is not marked as default.

[cueckoo]

Original reply by @mpvl in cuelang/cue#31 (comment)

Ah, yes. One needs to use the -c option now, for concrete or compile, to expose these errors.