docs : embedding schema in generated code

[schafle]

I recently realized that we have been using wrong configuration. Because we don't have schema file and generated code in the same directory embedding schema in the generated code was not possible. I fixed it in our code but also wanted to fix the example code and documentation of gqlgen for federation examples.

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

[coveralls]

Coverage increased (+0.08%) to 75.233% when pulling 12e967b on schafle:embed-federation-schema into b66fff1 on 99designs:master.

[StevenACoffman]

Hey, just a heads up that I haven't forgotten about this, but I've been vacationing, and in the past there's been problems when I reviewed/merged PRs using my phone without trying them out fully. In particular, changing the documentation like this means I want someone (usually me) to go through all the tutorial's steps and verify there's nothing confusing or broken for new users. I reaaaally wish the tutorial was somehow automated to be scraped and ran as an end-to-end test or something, but right now it's not.

I appreciate your contribution, and I'm sorry for the delay. Thanks for your patience!