Fix Functional Requirements

[Oguzoz1]

Fix requirements according to the to-do list listed below

• [x] Add introduction to the requirements.
• [x] Sub-group the requirements and get all the definitions for all sub-groups in requirement manner.
• [x] Instead of using unordered lists, list the requirements. (Unique ID)
• [x] Get rid of non-defined vocabulary and be more specific. (Ex: error message but what error message? Pop-up but what is the pop up?)

[Oguzoz1]

All requirements are revisioned, sub-grouped and given more details.