EDITING: (GET-STARTED) Simplify and actualize `GetStarted` section

[azinit]

Problem

• The current tutorial can not be called a “quick start", because it contains a lot of details (for seniors - redundant, for juniors - not enough)
• Also, he is too tied to React, which knocks other people down
• In addition, the tutorial does not teach the application of the basics of the "slicing UI" methodology well

Subtasks

• [ ] #454
• [ ] #455
• [ ] If need, add more tutorials... (impl-speficic, quick-migration, ...)