DISCOVERY: (QUICK-PROMO) Refine Intro-usecase for users

[azinit]

Blocked by #420

Description

At the moment, our overview-oriented section "Intro" fulfills several goals:

• To Promote methodology
• To Introduce methodology

But it would be much better to spread this content to Landing and GetStarted section

And as result:

• We'll get less redundant sections
• We'll get Index page, without redundant info
• Our Landing'll start promote as it should
• Our GetStarted'll start introduce as it should

Subtasks

• [ ] #420
• [ ] #178
• [x] #480
• [ ] #448
• [ ] #449
• [ ] #450
• [ ] #451

Reference

Gatsby docs

[azinit]

https://github.com/feature-sliced/documentation/discussions/411

[azinit]

Results of discussions

• Summary of discussions
• @illright draft
• About intro-usecases