Add example for building schema from IDL

[symm]

I couldn't find it documented so wrote an example of how to use BuildSchema with IDL shorthand and then wire it up to some resolvers.

[coveralls]

Coverage remained the same at 93.874% when pulling 81376e7 on symm:shorthand-docs into bc6a7a3 on webonyx:master.

[vladar]

Thanks a lot!

[jasonbahl]

@symm This is pretty sweet. . .but doesn't this cause all the resolve functions in the rootValue to be executed every time GraphQL is executed whether the field is queried for or not? Or is the GraphQL internals smart enough to only execute the resolvers for that rootValue the same it does for the rest of the resolvers?

[symm]

@jasonbahl The anonymous functions will only be executed if the GraphQL lib needs to resolve them. You can verify by putting a sleep call on the Addition resolver and calling the echo method 👍

That said, it's just a demo and I'd fetch the resolvers from a DI container in a real app.