Update intro_to_nuclei.md

[santosomar]

This pull request includes several changes to the recon/intro_to_nuclei.md file to enhance clarity and provide additional practical examples for using Nuclei. The most important changes include revising key sections for improved readability and adding detailed examples and scenarios for running Nuclei scans.

Improvements to documentation clarity:

• Revised the description of template components to make it clearer and more concise.
• Simplified the example CVE detection template introduction for better readability.

Addition of practical examples:

• Added a new section with basic usage examples of running Nuclei against a single target and specifying templates or directories.
• Included detailed commands for running Nuclei scans with specific templates, categories, and rate limits.
• Provided guidance on interpreting Nuclei scan results and outputting them to files in various formats.
• Added advanced usage examples, including workflows, tagging, and integration with other tools.
• Summarized a practical example scenario to demonstrate a comprehensive approach to using Nuclei for vulnerability scanning.