Add some example in docs about compare screenshot

[NikolaySolodukhin]

Hey! I read the documentation and did not find a single example about the comparison of screenshots could not supplement the documentation and give examples

[th0car]

This would be valuable - just one or two examples - nothing fancy. I have previously been using Gemini for image comparison testing but it's difficult to know whether to move on to Hermione or not since I can't see to what extent Hermione matches Gemini when creating and executing this type of tests.

[sipayRT]

https://github.com/gemini-testing/hermione#assertview