Feature "full" does not enable feature "test-util"

[wqfish]

The document (https://docs.rs/tokio/1.0.1/tokio/index.html#feature-flags) says

full: Enables all Tokio public API features listed below.

But the test-util feature doesn't seem to be enabled with full. Probably either include the test-util feature with full, or clarify this in the document?

[Darksonn]

I've updated this as a doc issue and help-wanted in case anyone wants to update the doc. It shouldn't be enabled in full, since you should mainly be using it in tests.