docs(v2): Improve intro doc (#4770)

* Intro documentation refactoring

* useless images

* improve the intro doc

website/docs/contributing.md → website/community/3-contributing.md

@@ -3,7 +3,7 @@ id: contributing
 title: Contributing
 ---
 
-[Docusaurus 2](https://docusaurus.io/) is currently under alpha development. We have [early adopters who already started using it](/showcase). We are now welcoming contributors to collaborate on the next Docusaurus.
+[Docusaurus 2](https://docusaurus.io/) is currently under development. We have [early adopters who already started using it](/showcase). We are now welcoming contributors to collaborate on the next Docusaurus.
 
 The [Open Source Guides](https://opensource.guide/) website has a collection of resources for individuals, communities, and companies who want to learn how to run and contribute to an open source project. Contributors and people new to open source alike will find the following guides especially useful:
 
@@ -18,7 +18,7 @@ Facebook has adopted a Code of Conduct that we expect project participants to ad
 
 There are many ways to contribute to Docusaurus, and many of them do not involve writing any code. Here's a few ideas to get started:
 
-- Start using Docusaurus 2! Go through the [Getting Started](installation.md) guides. Does everything work as expected? If not, we're always looking for improvements. Let us know by [opening an issue](#reporting-new-issues).
+- Start using Docusaurus 2! Go through the [Getting Started](/docs/installation) guides. Does everything work as expected? If not, we're always looking for improvements. Let us know by [opening an issue](#reporting-new-issues).
 - Look through the [v2.0 issues](https://github.com/facebook/docusaurus/labels/v2). If you find an issue you would like to fix, [open a pull request](#your-first-pull-request). Issues tagged as [_Good first issue_](https://github.com/facebook/docusaurus/labels/Good%20first%20issue) are a good place to get started.
 - Help us making the docs better. File an issue if you find anything that is confusing or can be improved. We also have [an umbrella issue for v2 docs](https://github.com/facebook/docusaurus/issues/1640) where we are planning and working on all v2 docs. You may adopt a doc piece there to work on.
 - Take a look at the [features requested](https://github.com/facebook/docusaurus/labels/enhancement) by others in the community and consider opening a pull request if you see something you want to work on.

website/docs/cli.md

@@ -95,7 +95,7 @@ For advanced minification of CSS bundle, we use the [advanced cssnano preset](ht
 
 :::caution
 
-We highly discourage swizzling of components until we've reached a Beta stage. The components APIs have been changing rapidly and are likely to keep changing until we reach Beta. Stick with the default appearance for now if possible to save yourself some potential pain in future.
+We discourage swizzling of components during the Docusaurus 2 beta phase. The theme components APIs are likely to evolve and have breaking changes. If possible, stick with the default appearance for now.
 
 :::
 

website/docs/installation.md

@@ -3,11 +3,13 @@ id: installation
 title: Installation
 ---
 
-Docusaurus is essentially a set of npm [packages](https://github.com/facebook/docusaurus/tree/master/packages) that can be installed over npm.
+Docusaurus is essentially a set of npm [packages](https://github.com/facebook/docusaurus/tree/master/packages).
 
 :::tip
 
-Use **[new.docusaurus.io](https://new.docusaurus.io)** to test Docusaurus immediately in CodeSandbox.
+Use the **[Fast Track](introduction.md#fast-track)** to understand Docusaurus in **5 minutes ⏱**!
+
+Use **[new.docusaurus.io](https://new.docusaurus.io)** to test Docusaurus immediately in your browser!
 
 :::