Restructure tutorial to enable attendees to choose platform and shorten tutorial

[amakarudze]

Issue description

The installation section is too long because there are many options. Just like someone is able to choose the language they are using, a user should be able to choose their platform among the options: ChromeBook, RunCode, Mac OSX, Linux or Windows and follow sections related to the platform.

This means re-ordering the paragraphs related to each operating system/platform so users do not need to spend time reading all the notes to skip sections if they are not using that operating systems.

Language

No.

Operating system

This pertains to all operating systems covered in the tutorial.

This issue is related to #1777 which is another great idea. Since #1777 already suggests re-ordering the chapters these two issues could be tackled at the same time so that all the restructuring is done at the same time.