fix(docs): should fix #399 and unify the markdown syntax

[EmileRolley]

Related issue: #399

Major changes are:

• Indent code blocks inside lists.

  Sould fix Documentation bug: markdown syntax errors #399 , but to be sure we have to wait until the GitHub page is updated.

• Unify the markdown syntax for the tutorial steps (e.g. new line after headings and - for all list items).

[erikmd]

Thanks @EmileRolley, the diff looks very fine.

So, I'm merging it; and as you suggest, let's double-check the outcome afterwards.

[erikmd]

Yes, it looks very OK now: for example, I saw no more dangling ``` here and there.

So thanks @EmileRolley for your PR and for the small typos you corrected along the way!

[EmileRolley]

You are welcome, glad to see that it worked!