graphql.md: add "MediaObject Normalization" chapter

[timble-one]

graphql-normalizer needs to be injected

[vinceAmstoutz]

@71m024 Tanks for your contribution!

Can you please add more explanation on the “Why”?

Also, can you add an injection example for Laravel? As you can see here with an example of injection, we now document both Symfony and Laravel (since 4.0).

[vinceAmstoutz]

@timble-one Do you plan to keep going?

[timble-one]

@vinceAmstoutz I made it i little bit clearer, that the injected normalizer must be replaced with the one from the graphql namespace. Otherwise it won't work if you just do it like it is done here: https://api-platform.com/docs/symfony/file-upload/
(this link is mentioned at the start of the chapter)

I have never used Laravel before. If this must be ported to the Laravel Documentation it should be done be someone who has experience.

[timble-one]

I think the linting Problem is not caused by this PR.

[vinceAmstoutz]

I think the linting Problem is not caused by this PR.

@timble-one Yes you're right, could you please rebase it from the 4.1 branch?

[vinceAmstoutz]

Should be great for me after theses changes @timble-one

[vinceAmstoutz]

LGTM, thanks @timble-one!