docs(all): Added documentation to missing parts

src/entities/card.rs

@@ -1,7 +1,14 @@
+//! Module representing cards of statuses.
+
+/// A card of a status.
 #[derive(Debug, Clone, Deserialize)]
 pub struct Card {
+    /// The url associated with the card.
     pub url: String,
+    /// The title of the card.
     pub title: String,
+    /// The card description.
     pub description: String,
+    /// The image associated with the card, if any.
     pub image: String,
 }