Add model for comments

[YashTrivedi21]

• Add a mongoose model for comments. Comments will appear below every single order's page
• Fields should be description, order id(foreign key), user id(foreign key).

[1337-ishaan]

Pls assign

[YashTrivedi21]

Done!

[1337-ishaan]

@YashTrivedi21 pls check #37

[1337-ishaan]

Why does'nt it have the hacktoberfest-accepted label?

[YashTrivedi21]

The repo as well as the issue has hactoberfest label. But still I will add the hactoberfest-accepted label just in few minutes.