feat(feed): impl Display for annotation types

crates/synd_feed/src/types/category.rs

@@ -1,4 +1,7 @@
-use std::borrow::Cow;
+use std::{
+    borrow::Cow,
+    fmt::{self, Display},
+};
 
 use serde::{Deserialize, Serialize};
 use thiserror::Error;
@@ -37,6 +40,12 @@ impl<'a> Category<'a> {
     }
 }
 
+impl<'a> Display for Category<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.0.as_ref())
+    }
+}
+
 #[cfg(feature = "graphql")]
 #[async_graphql::Scalar]
 impl<'s> async_graphql::ScalarType for Category<'s> {

crates/synd_feed/src/types/requirement.rs

@@ -1,5 +1,8 @@
 use serde::{Deserialize, Serialize};
-use std::str::FromStr;
+use std::{
+    fmt::{self, Display},
+    str::FromStr,
+};
 
 /// `Requirement` expresses how important the feed is
 /// using an analogy to [RFC2119](https://datatracker.ietf.org/doc/html/rfc2119)
@@ -26,3 +29,13 @@ impl FromStr for Requirement {
         }
     }
 }
+
+impl Display for Requirement {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Requirement::Must => f.write_str("MUST"),
+            Requirement::Should => f.write_str("SHOULD"),
+            Requirement::May => f.write_str("MAY"),
+        }
+    }
+}