Add Postman case study

[Relequestual]

This case study is a reposting, with permission, from the Postman blog: https://blog.postman.com/how-postman-uses-json-schema

Thanks to @jviotti for being such a great internal ally and finding out lots of useful information about where JSON Schema is used in Postman.

Closes json-schema-org/community#215

[jviotti]

Any time!

[Julian]

I left some minor comments just making sure it was clear that the voice of "us" here is "Postman" not "JSON Schema" -- probably good to change those. It might also be good to have a very short disclaimer saying "A number of members of the JSON Schema organization are employed by Postman, but this post is not sponsored content." or whatever -- but not critical, think it's probably fine to leave it out too. But overall, lgtm, feel free to merge as far as I'm concerned.

[jviotti]

Looks good to me!

[gregsdennis]

Is there no build for this? It looks like you have some styled elements. It'd be good to verify those work with the preview.

[gregsdennis]

Content looks good. Some formatting questions, and I agree with @Julian that the "we" first person feels odd here. Maybe you just missed one.

[Relequestual]

@gregsdennis I believe I managed to resolve all your comments.
Here's a render:

View render

[gregsdennis]

Still not sure why the site preview isn't available, but that's a separate issue.

[Relequestual]

Still not sure why the site preview isn't available, but that's a separate issue.

Previews for CloudFlare do not work for forks. For the new site, we will have to have a policy of JSON Schema team making PRs on branches as opposed to forks.