Add examples for making Tokio async await calls

[jsoneaday]

[kjvalencik]

@jsoneaday Is there something you would like to see added that isn't in the tokio-fetch example?

[Rush]

It's an old example. No longer works with 1.0.

[kjvalencik]

@Rush Thanks for the heads up! I'll make a note to update these examples for the upcoming 1.0 release!