improve uefi::Error documentation

Author: phip1611

uefi/src/result/error.rs

@@ -1,8 +1,11 @@
+//! Module for UEFI-specific error encodings. See [`Error`].
+
 use super::Status;
 use core::fmt::{Debug, Display};
 
-/// Errors emitted from UEFI entry point must propagate erroneous UEFI statuses,
-/// and may optionally propagate additional entry point-specific data.
+/// An UEFI-related error with optionally additional payload data. The error
+/// kind is encoded in the `status` field (see [`Status`]). Additional payload
+/// may be inside the `data` field.
 #[derive(Debug, PartialEq, Eq)]
 pub struct Error<Data: Debug = ()> {
     status: Status,