Datacenter struct not exported.

[Lorak-mmk]

Struct Datacenter defined here:

scylla-rust-driver/scylla/src/transport/cluster.rs

Lines 54 to 58 in f145cea

	#[derive(Clone, Debug)]
	pub struct Datacenter {
	pub nodes: Vec<Arc<Node>>,
	pub rack_count: usize,
	}

is not exported in transport's mod.rs, which makes it's documentation inaccessible (https://docs.rs/scylla/latest/scylla/transport/struct.ClusterData.html - can't click it the return type of get_datacenters_info).

[wprzytula]

Ref #977

[muzarski]

Closing since #1094 was merged