Add an example to Serialize

serde/src/ser/mod.rs

@@ -200,6 +200,29 @@ pub trait Serialize {
     /// See the [Implementing `Serialize`] section of the manual for more
     /// information about how to implement this method.
     ///
+    /// ```rust
+    /// use serde::ser::{Serialize, Serializer, SerializeStruct};
+    ///
+    /// struct Person {
+    ///     name: String,
+    ///     age: u8,
+    ///     phones: Vec<String>,
+    /// }
+    ///
+    /// // This is what #[derive(Serialize)] would generate.
+    /// impl Serialize for Person {
+    ///     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    ///         where S: Serializer
+    ///     {
+    ///         let mut s = serializer.serialize_struct("Person", 3)?;
+    ///         s.serialize_field("name", &self.name)?;
+    ///         s.serialize_field("age", &self.age)?;
+    ///         s.serialize_field("phones", &self.phones)?;
+    ///         s.end()
+    ///     }
+    /// }
+    /// ```
+    ///
     /// [Implementing `Serialize`]: https://serde.rs/impl-serialize.html
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where