Adding part of non-functional requirements

[BElifb]

To-do:

• Adding performance and portability non-functional requirements to the Requirements wiki page.
• Make additions to the glossary if you see anything missing

Deadline: 14.03.2022
Revision Deadline: 20.03.2022

[BElifb]

I have added the Non-Functional part along with portability and performance. Please review at requirements. @mumcusena @mustafa-cihan @kostanya

[BElifb]

Also added Art Item, Exhibition, Forum, Verified, Level, Interaction and popularity to the glossary.

[BElifb]

Sufficient for the time being. No additions needed presently.