Add guide - Creating exception list

[rajlearner17]

Guide purpose

• Should be in guides/using-guardrails/nunjucks
• How do I create array and create map for nunjucks to implement exception
  (Can be specific example such as list of account to be exempted from any control or list of S3 buckets exempted from the versioning control etc.)

Target audience
Specify who this guide is intended for (e.g., beginners, advanced users, specific roles).

Categories
Proposed primary category and categories where this guide would fit best. (e.g., Getting Started, Best Practices, Troubleshooting, Concepts etc).

Outline
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