docs: add missing backticks in documentation

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

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>,