docs/nia: recommend sensitive variables for module authoring (#9692)

website/content/docs/nia/installation/requirements.mdx

@@ -162,7 +162,8 @@ Network infrastructure differs vastly across teams and organizations, and the au
 1. Identify areas in the module where practitioners could tailor the automation to fit their infrastructure.
 2. Declare input variables and insert the use of variables throughout module resources to expose these options to practitioners.
 3. Include descriptions to capture what the variables are and how they are used, and specify [custom validation rules for variables](https://www.terraform.io/docs/configuration/variables.html#custom-validation-rules) to provide context to users the expected format and conditions for the variables.
-4. Set reasonable default values for variables that are optional, and omit default values for variables that are required module arguments.
+4. Set reasonable default values for variables that are optional, or omit default values for variables that are required module arguments.
+5. Set the [sensitive argument](https://www.terraform.io/docs/language/values/variables.html#suppressing-values-in-cli-output) for variables that contain secret or sensitive values. When set, Terraform will redact the value from output when Terraform commands are run.
 
 Terraform is an explicit configuration language and requires variables to be declared, typed, and passed explicitly through as module arguments. Consul-Terraform-Sync abstracts this by creating intermediate variables at the root level from values intended for the module. These values are configured by practitioners within the [`task` block](/docs/nia/configuration#variable_files). Value assignments are parsed to interpolate the corresponding variable declaration and are written to the appropriate Terraform files. A few assumptions are made for the intermediate variables: the variables users provide Consul-Terraform-Sync are declared and supported by the module, matching name and type.