refactor: rename DTree to DValue

site/doc/pages/yaml_decode.txt

@@ -1,19 +1,19 @@
 :sig
-DTree yaml_decode(String s)
+DValue yaml_decode(String s)
 
 :params
 s : YAML source string
-return value : decoded DTree
+return value : decoded DValue
 
 :see
 >markup
 yaml_encode
 json_decode
 xml_decode
-0_DTree
+0_DValue
 
 :content
-Parses a practical YAML subset into a `DTree`.
+Parses a practical YAML subset into a `DValue`.
 
 `yaml_decode()` is designed for concise UCE config files. It intentionally avoids full YAML schema behavior and does not support anchors, aliases, tags, directives, or complex inline collection syntax.
 
@@ -30,7 +30,7 @@ String source = "app:\n"
 	"    - site\n"
 	"    - cache\n";
 
-DTree cfg = yaml_decode(source);
+DValue cfg = yaml_decode(source);
 
 cfg["app"]["name"].to_string();       // UCE Starter
 cfg["app"]["debug"].to_bool();        // true