Go SDK - Create standard doc string templates for T TArgs TInput TOutput that clarify usage

[EvanBoyle]

Right now it can be very hard to determine what form of T to construct when using nested types. This cloud trail argument:

https://github.com/pulumi/pulumi-aws/blob/c29dcf1b7f3209874af908b4fa94c81991b5adde/sdk/go/aws/cloudtrail/trail.go#L155

Leads to this overwhelming type file with no clarity on what the proper form of the type should be:

https://github.com/pulumi/pulumi-aws/blob/c29dcf1b7f3209874af908b4fa94c81991b5adde/sdk/go/aws/cloudtrail/pulumiTypes.go

We should be able to come up with a standard doc string for each form of T TArgs TInput and TOutput that is specific about the intended usage, for instance:

// T may be used to specify detailed instructions about how to build a container.
// T is the raw representation of the type.

// TArgs is the pulumified version of T where are members are outputs. 
// Construct TArgs as an input to NewDockerBuild(...)

The work here is to:

1. Define the standard template for each form of T
2. Update our code generators to put these in in our SDK types for go (aws, azure, gcp).

Came up in pulumi/pulumi-docker#147 (comment)