Update info on Twig namespaces

[ameotoko]

This updates Twig Namespaces section with more precise information about which bundle templates directory is registered automatically, and which can optionally be added.

[fritzmg]

In Symfony 6 the default is different. May be we should link to the Symfony Docs instead?

[ameotoko]

What do you mean? The section on namespaces is identical between 5.4 and 6.1 branches.

[fritzmg]

I mean https://symfony.com/doc/current/bundles/best_practices.html#directory-structure

In Symfony 6 you can extend from AbstractBundle which returns the root directory of the package in getPath by default.

[ameotoko]

Will the example on creating a bundle be updated as well?

[fritzmg]

Yes, I definitely want to update that as well (though not by using AbstractBundle).

[ameotoko]

How about now, @fritzmg?

[fritzmg]

Unfortunately there is a conflict with this PR now. The section has moved to https://github.com/contao/docs/blob/main/docs/dev/framework/templates/architecture.md

[ameotoko]

I rebased and brought my edits to the new location "as is". However, I was not following the core team's work in past months, so I may not be on top of the things with this PR anymore.

[fritzmg]

Thank you @ameotoko