Update docs for clarity around creating KfDef YAML

[tmarkiewicz]

In the documentation, after clicking 'Create KfDef' the user is taken to a screen where they're shown the form view and given the option for YAML. This change adds clarity, as on a quick glance it would appear the YAML view is not there. Language was added to make this more obvious.

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[lresende]

LGTM

[akchinSTC]

LGTM