[docs] Add and/or revise "Overview" pages for each MUI product

[samuelsycamore]

Tasks

• create Base Overview - [docs] Add "Overview" page to Base docs #32310
• create Material UI Overview - [docs] Add "Overview" page to Material UI docs #32643
• create System Overview - [docs] Create, revise, and expand System "Getting started" docs #33503
• revise X Overview - [docs] Revise and split up "Overview" page into "Getting started" section

Summary 💡

MUI X has a newly published Overview page, and I think we should take it a step further and create something similar for our other products.

I was reviewing the Tina CMS docs and I really like their Overview page, which is the default when you click through to their docs. It gives a brief intro of the product, and then explains the key features/selling points.

Instead of directing the reader to Installation docs for Material UI and Base, I think we should follow Tina's example and create pages to answer "Why?" for each of these products.

This way, when a new user lands in our docs and isn't sure which product is best for their project, they'll be able to find a quick summary of each that explains its main selling points.

Examples 🌈

Motivation 🔦

With the release of new documentation restructuring, I'm not sure that "Installation" is the best page to serve as the landing page for each product. This is a great opportunity to clarify our branding and do some (tasteful 😅) marketing in our docs.

[siriwatknp]

This is a great opportunity to clarify our branding and do some (tasteful 😅) marketing in our docs.

Could not agree more!

[samuelsycamore]

Boilerplate for Overview pages

---
title: Overview
---

# {{productName}} - Overview

<p class="description">Quick description.</p>

## Introduction

2-3 short paragraphs.

## Advantages of {{productName}}

list of 3-4 items.

## {{productName}} vs. {{otherSimilarProductOfOurs}}

2-3 short paragraphs explaining how product differs from our other offerings.