Fix Request::new documentation (#4560)

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

@@ -176,7 +176,7 @@ impl<'a, T> Request<'a, T> {
 }
 
 impl<'a, T: Default> Request<'a, T> {
-	/// Create new Request builder with given URL and body.
+	/// Create a new Request builder with the given URL.
 	pub fn new(url: &'a str) -> Self {
 		Request::default().url(url)
 	}