docs: add missing backticks in documentation

this improve readability of documentation.
enable associated clippy lint `doc_markdown`

src/util/encode.rs

@@ -1,7 +1,7 @@
 use serde::{Deserialize, Serialize};
 
-/// Serialize to MessagePack, without versioning
-/// (see garage_util::migrate for functions that manage versioned
+/// Serialize to `MessagePack`, without versioning
+/// (see `garage_util::migrate` for functions that manage versioned
 /// data formats)
 pub fn nonversioned_encode<T>(val: &T) -> Result<Vec<u8>, rmp_serde::encode::Error>
 where
@@ -13,8 +13,8 @@ where
 	Ok(wr)
 }
 
-/// Deserialize from MessagePack, without versioning
-/// (see garage_util::migrate for functions that manage versioned
+/// Deserialize from `MessagePack`, without versioning
+/// (see `garage_util::migrate` for functions that manage versioned
 /// data formats)
 pub fn nonversioned_decode<T>(bytes: &[u8]) -> Result<T, rmp_serde::decode::Error>
 where