Routing: add explanation for the "_fragment" parameter

[alexislefebvre]

Add explanation about this PR: symfony/symfony#12979

Presented in http://symfony.com/blog/new-in-symfony-3-2-routing-improvements

I copy-pasted the start of the announcement as the explanation since I couldn't have found a better explanation. I hope that won't be a problem.

[xabbuh]

This change looks good to me. But I think we should add a versionadded directive which explains that support for this parameter was introduced in 3.2.

[alexislefebvre]

Thanks for the review @xabbuh, I added versionadded.

[javiereguiluz]

I know it's a bit verbose, but in Symfony Docs the versionadded directive is used like this:

.. versionadded:: 3.2
    The ``_fragment`` parameter was introduced in Symfony 3.2.

[javiereguiluz]

👍

Status: reviewed

[stof]

IMO, this is the wrong place for it, as you won't use _fragment in route patterns.

It should rather be explained in a section near Generating URLs with Query Strings

[alexislefebvre]

@javiereguiluz I updated the versionadded part. What do you think of the comment of stof? Should I add a new section near Generating URLs with Query Strings? Thanks.

[wouterj]

Hi @alexislefebvre!

I've merged your pull request and fixed a syntax error in 0a22dda. I think it's a nice idea to also document this in the generating section indeed. Not sure if I would add a new section or just add it to the main section.

Feel free to propose another PR doing this. For now, thanks a lot for documenting this nice feature!