Add warning to Berkshelf, Roles, Environments documentation

[tas50]

Is your feature request related to a problem? Please describe.

We need to make it clear to users that the future is Policyfiles. We should be warning in these documents that this is a legacy workflow and new users should not adopt these patterns.

Describe the solution you'd like

A nicely worded warning on each page that documents legacy workflows

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.