[#474] DOCS: Add guide 'How Selene compares to other frameworks' NEEDS TO CONTINUE

[hotenov]

This PR for #474

I leave some comments here in order to help a person who will continue this task (guide) in the future. I think it will be Yasha himself :).

1) General warnings and reminders to notes in the text

1.1) Need careful proofreading before publish: Many comments are placed by me without any formatting (highlighting). And also part of them contains instructions what need to add (describe), because I have no expertise in many points.

1.2) A few notes have user's quotes from private chat(s) for understanding context.

1.3) Some info might be outdated (draft was written in Mar-Apr'2023)

1.4) Blank sections about frameworks from Java and JS worlds (need to write them from the scratch)


2) Comments by @yashaka after first review about examples:

2.1) Need to update example for Selene (from updated  README)

2.2) Change the order of the tabs (from Selenium to Selene, i.e. "from bad to good"). But to my opinion Selene tab should be the first, because users always see it when they open this page.

2.3) Yasha wanted to remove  'assert' words for pylenium (because we don't use assert for selene example), BUT
	This is a recommendation on their docs
	https://docs.pylenium.io/elements-commands/length
	because it returns INT :) -> We can add this as its disadvantage :)
	also for others `should`s the author writes `assert` in his examples:
	https://docs.pylenium.io/element-commands/should#examples
	
2.4) Remove variables for selectors, because this is supported by all them. Only locators are "lazy". (as I'm not big expert in Selenium and Selene, need clear difference when using python variables is a killer feature of a wrapper).

	From private chat with Yasha:
	еще вариант чтобы не нагромождать... в первых примерах. -можно вообще обойтись без переменных
	и потом просто в отдельном разделе поднять тему "локаторов сохраненных в переменных", описать зачем это нужно
	для пейджобджектов типа
	и показать что в селениуме - мы сохраняем локаторы, а в селене можем сохранять элементы