[Enhancement] Improve README readability — clear Q&A separation, numbered questions & SQL syntax highlighting

[MOHIT-SOLANKII]

Problem

The current README.md is very hard to read because:

• Questions and answers both use ### headings — there is no visual difference between them
• The Table of Contents is broken — every row shows "1" instead of a proper number
• SQL code is written as plain text with no syntax highlighting
• No separators between Q&A sections make it one giant wall of text
• 175+ questions with zero visual structure is overwhelming for any reader

What Was Changed

• Added sequential numbering to every question (Q1 to Q175)
• Added ✅ Answer: label before every answer for instant visual distinction
• Fixed the Table of Contents with proper numbering and working anchor links
• Wrapped all SQL code in ```sql code blocks for syntax highlighting
• Added --- horizontal rule separators between each Q&A
• Added a "How to Use This Guide" intro section at the top

Before vs After

Before:

What is a database?

A database is an organized collection of data...

What is DBMS?

A DBMS is a program that controls creation...

After:

Q1. What is a database?

✅ Answer:
A database is an organized collection of data...

Q2. What is DBMS?

✅ Answer:
A DBMS is a program that controls creation...

Notes

• No content was deleted or modified — only formatting was improved
• All 175 Q&As are intact
• File renders correctly in GitHub Markdown preview