Add Default trait to Settings

src/settings/mod.rs

@@ -370,6 +370,28 @@ impl Settings {
     }
 }
 
+impl Default for Settings {
+    /// Creates a new empty instance of [`Settings`]
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// let s = lang_evolve_core::settings::Settings::default();
+    /// let content_yaml = r#"---
+    /// version: "1"
+    /// categories: {}
+    /// rules: []"#;
+    /// let content_json = r#"{"version":"1","categories":{},"rules":[]}"#;
+    /// assert_eq!(content_yaml, serde_yaml::to_string(&s).unwrap());
+    /// assert_eq!(content_json, serde_json::to_string(&s).unwrap());
+    /// ```
+    ///
+    /// [`Settings`]: ./settings/struct.Settings.html
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 use std::str::FromStr;
 impl FromStr for Settings {
     type Err = serde_yaml::Error;