When content attribute is used in files promises, `create => "false"` is ignored

When content attribute is used in files promises, `create => "false"` is ignored. The create attribute should have same behavior as when template methods mustache and inline_mustache is used. I.e.

• If `create => "true"` is specified; the file is created even though rendering fails.
• If `create => "false"` is specified; the file is never created.
• If not specified; the file is created by default, but only upon successful rendering.

Also mention the content attribute in the comment where this logic is implemented for the mustache template methods.