Fix multiple documentation issues concerned by clippy

kernel/libs/aster-util/src/safe_ptr.rs

@@ -24,13 +24,13 @@ pub use typeflags_util::SetContain;
 /// More specifically, there are three major restrictions.
 ///
 /// 1. A safe pointer can only refer to a value of a POD type `T: Pod`,
-/// while raw pointers can do to a value of any type `T`.
+///    while raw pointers can do to a value of any type `T`.
 /// 2. A safe pointer can only refer to an address within a virtual memory object
-/// of type `M: VmIo` (e.g., VMAR and VMO), while raw pointers can do to
-/// an address within any virtual memory space.
+///    of type `M: VmIo` (e.g., VMAR and VMO), while raw pointers can do to
+///    an address within any virtual memory space.
 /// 3. A safe pointer only allows one to copy values to/from the target address,
-/// while a raw pointer allows one to borrow an immutable or mutable reference
-/// to the target address.
+///    while a raw pointer allows one to borrow an immutable or mutable reference
+///    to the target address.
 ///
 /// The expressiveness of safe pointers, although being less than that of
 /// raw pointers, is sufficient for our purpose of writing an OS kernel in safe

kernel/libs/comp-sys/component-macro/src/lib.rs

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: MPL-2.0
 
 //！This crate defines the component system related macros.
-//!
 
 #![feature(proc_macro_diagnostic)]
 #![allow(dead_code)]

kernel/libs/keyable-arc/src/lib.rs

@@ -10,9 +10,9 @@
 //!
 //! 1. It implements the `Eq` and `Hash` traits.
 //! 2. The two values of `k1` and `k2` of type `K` equal to each other,
-//! if and only if their hash values equal to each other.
+//!    if and only if their hash values equal to each other.
 //! 3. The hashes of a value of `k` of type `K` cannot change while it
-//! is in a map.
+//!    is in a map.
 //!
 //! Sometimes we want to use `Arc<T>` as the key type for a hash map but cannot do so
 //! since `T` does not satisfy the properties above. For example, a lot of types