Add missing trailing commas for all examples

[javiereguiluz]

As discussed in #8319, there are some code examples where we don't include the trailing comma in the last element of the arrays. For example here: https://github.com/symfony/symfony-docs/blob/master/service_container.rst.

So let's review all of them 😄

[javiereguiluz]

@DylanDelobel is going to give a shot at this, so we'll wait for his pull requests 😄

[javiereguiluz]

Fixed by #9238.