fix: update PostgreSQL configuration instructions for Docker environment

[TanvirTian]

Description

This PR fixes and clarifies PostgreSQL configuration instructions in the Docker documentation.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring (no functional changes)
• Performance improvement
• Test updates

Changes Made

• Clarified environment variable changes required after copying .env

Testing Checklist

• Unit tests added or updated
• Integration tests pass
• Manual testing completed
• Documentation updated (if applicable)
• All existing tests pass

Code Quality Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation to reflect my changes
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Additional Context

N/A

[ifrunruhin12]

change this and we are good to go

[ifrunruhin12]

Remove these emojis please. only saying correct and incorrect is enough. as you will notice our documentation has very minimal (close to none) emoji usage right now. some place where there is still irrelevant emoji we will remove most of it as well. but when adding new doc we won't be adding emojis anymore cause our docs was designed with visually appealing theme to begin with