Add secure database user setup

[northernmonkey98]

✍️ Add Blog: Setting Up and Securing a Database User for Grafana

Summary

This PR adds a new documentation article titled "Setting Up and Securing a Database User for Grafana". The guide walks through:

• Creating read-only users in MySQL using SQL
• Connecting Grafana securely to databases
• Best practices for database security
• Using environment variables to manage credentials

📌 Motivation

To help users configure secure database access for Grafana in a beginner-friendly and production-safe way

✅ Changes

• New Markdown file: secure-grafana-database-user.md
• Includes:
  • SQL examples for MySQL
  • Grafana connection steps
  • Security best practices

🧪 Testing

• Verified all code blocks and syntax

🔜 To Do

• Add photo and video on how to do this within the hedisql gui

[northernmonkey98]

this is my first time ever in 14 years doing a pull request please let me know what i can do better and any mistakes i made