docs: add missing backticks in documentation

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

src/api/s3/error.rs

@@ -50,11 +50,11 @@ pub enum Error {
 	#[error("Parts given to CompleteMultipartUpload do not match uploaded parts")]
 	InvalidPart,
 
-	/// Parts given to CompleteMultipartUpload were not in ascending order
+	/// Parts given to `CompleteMultipartUpload` were not in ascending order
 	#[error("Parts given to CompleteMultipartUpload were not in ascending order")]
 	InvalidPartOrder,
 
-	/// In CompleteMultipartUpload: not enough data
+	/// In `CompleteMultipartUpload`: not enough data
 	/// (here we are more lenient than AWS S3)
 	#[error("Proposed upload is smaller than the minimum allowed object size")]
 	EntityTooSmall,

src/api/s3/list.rs

@@ -939,7 +939,7 @@ fn common_prefix<'a>(object: &'a Object, query: &ListQueryCommon) -> Option<&'a
 	}
 }
 
-/// URIencode a value if needed
+/// `URIencode` a value if needed
 fn uriencode_maybe(s: &str, yes: bool) -> s3_xml::Value {
 	if yes {
 		s3_xml::Value(uri_encode(s, true))

src/api/s3/router.rs

@@ -309,7 +309,7 @@ pub enum Endpoint {
 impl Endpoint {
 	/// Determine which S3 endpoint a request is for using the request, and a bucket which was
 	/// possibly extracted from the Host header.
-	/// Returns Self plus bucket name, if endpoint is not Endpoint::ListBuckets
+	/// Returns Self plus bucket name, if endpoint is not `Endpoint::ListBuckets`
 	pub fn from_request<T>(
 		req: &Request<T>,
 		bucket: Option<String>,