address clippy & rustdoc warnings

The comment was out of date anyway, State::Live no longer takes a
snapshot_path argument.

substrate/primitives/runtime/src/offchain/http.rs

@@ -450,7 +450,7 @@ impl Headers {
 	/// and collect them on your own.
 	pub fn find(&self, name: &str) -> Option<&str> {
 		let raw = name.as_bytes();
-		for &(ref key, ref val) in &self.raw {
+		for (key, val) in &self.raw {
 			if &**key == raw {
 				return str::from_utf8(val).ok()
 			}