[Quick intro][The Architecture] autoload listing is outdated

[titomiguelcosta]

In the master repository, the autoload.php is outdated, listing 4.2, doesn't reflect the use of the composer autoload.

[Sgoettschkes]

The reference to composer was updated and I didn't find any outdated listing. This one can be closed @weaverryan

[wouterj]

ping @weaverryan

[Sgoettschkes]

ping @weaverryan

[wouterj]

This document does not talk about composer or does not have any outdated information which should be changed to composer.

The other quick tour articles are already updated in #1629 and #1996, so I'm going to close this issue.