Top-navigation bar - "Pomoc" button

[w1stler]

As a user, I want to see question mark icon at the top-nav bar, In order to get help about what I can do within the application

Context:

As a user I want to see question mark icon, which should trigger modal window with information about the application and how to use it.

Acceptance criteria:

• question mark icon should be visible at the top-nav bar
• modal window should be opened after clicking on this icon
• information about application should be displayed within modal window

TBS