highlight the of use of secret: true in pulumi templates

[desteves]

Problem description

• I had trouble finding the information that I needed:

When putting together a Pulumi template, it wasn't entirely obvious how to declare a secret variable, or that that was even a possibility. I ended up browsing through a few pulumi/templates to figure out how this is done. I think part of the issue may have been that our main templates page has a bunch of readily available solutions but no steps on how to define and create a template ourselves.

Affected product version(s)

Pulumi templates

Suggestions for a fix

Evaluate current docs pages wrt to template creation. Link to the Pulumi templates blog post as needed and/or take the blurb about the secret flag option and mention it in our docs.

We could also link to the Project file definition