Hello Piotr,
Where your documentation reads, "Note that these options are only available to be changed when you are on the Contact page in the theme customizer; once the customizer is open, open the Menu within the live preview and click on Contact."
>> I don't have Contact listed under the theme customizer (i.e. selecting Appearance > Customize does not have an option for contact.) The last option I have listed in the Customize option is "Frontpage".
Can you please assist? Thanks in advance!