chore: Only check missing_docs in lib

This also fires in examples and other places.

While docs in examples would be nice,
it isn't universally applicable and `allow`s would undermine the
examples.

Cargo.toml

@@ -17,7 +17,6 @@ include = [
 ]
 
 [workspace.lints.rust]
-missing_docs = "warn"
 rust_2018_idioms = "warn"
 unreachable_pub = "warn"
 unsafe_op_in_unsafe_fn = "warn"

src/lib.rs

@@ -1,6 +1,7 @@
 //! > DESCRIPTION
 
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![warn(missing_docs)]
 #![warn(clippy::print_stderr)]
 #![warn(clippy::print_stdout)]
 #![allow(non_snake_case)] // TODO: Delete me