Write paragraph 4.3 Design details

[illia-kriukov]

Describe design details and create:

• Use Case Diagram;
• Software Architecture;
• UML Class Diagram.
  See details in the report document https://docs.google.com/document/d/1fRFAq2tTrNhpVkYdQO_XkQ6LCikQSEq2bGiZA2Kungc/edit