[DOCS] Adding Environment variables summary

Documentation Type

README file

Current Issue

Missing env list and summary in README

Proposed Improvement

Add a table listing required env keys, short description, example format, and whether frontend/backend. This saves contributors time and reduces env-related issues.

Affected Sections

No response

Target Audience

New contributors

Additional Context

Hey @Sahilll94 Please assign this issue to me, I read Code of conduct, I am under ECwoC 26

Implementation

• I can write the documentation changes myself
• I can provide review and feedback
• I prefer to let others handle the implementation

Confirmation

• I have checked that this improvement isn't already covered elsewhere
• I have searched for existing documentation issues before creating this one