Investigate how to get custom GraphQL Scalar descriptions into the docs

[mkurapov]

Context

Currently, we have a few custom Scalars in our GraphQL schemas. The default GraphQL schemas correctly include the description (Boolean, Float, ID, etc) in our documentation on rafiki.dev (after being auto generated), but the custom scalars, JSONObject, UInt64, UInt8 do not have the descriptions added to them. We should figure out why, and make sure we can get those displaying properly.

Todos

• [ ] Get Scalar descriptions working properly on Rafiki.dev (write your own if you have to)
• [ ] Tag our writer @brad-dow once a PR is ready for review, so he can take a look

[brad-dow]

Here's the descriptions I've written. I'd love a technical review of these:

"""
The `UInt8` scalar type represents unsigned 8-bit whole numeric values, ranging from 0 to 255.
"""
scalar UInt8

"""
The `UInt64` scalar type represents unsigned 64-bit whole numeric values. It is capable of handling values that are larger than the JavaScript `Number` type limit (greater than 2^53).
"""
scalar UInt64

"""
The `JSONObject` scalar type represents JSON objects as specified by the [ECMA-404](http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf) standard.
"""
scalar JSONObject