refactor: rename DTree to DValue

site/doc/pages/zip_create.txt

@@ -1,5 +1,5 @@
 :sig
-bool zip_create(String zip_file_name, DTree entries)
+bool zip_create(String zip_file_name, DValue entries)
 
 :params
 zip_file_name : path to the archive to create
@@ -11,7 +11,7 @@ return value : `true` when the archive is written
 zip_list
 zip_read
 zip_extract
-DTree
+DValue
 
 :content
 Creates a ZIP archive at `zip_file_name`.
@@ -19,7 +19,7 @@ Creates a ZIP archive at `zip_file_name`.
 `entries` can be a simple map where each key is the archive member name and each value is the file content:
 
 ```uce
-DTree entries;
+DValue entries;
 entries["hello.txt"] = "Hello ZIP";
 entries["nested/readme.txt"] = "Nested file";
 zip_create("/tmp/example.zip", entries);
@@ -28,7 +28,7 @@ zip_create("/tmp/example.zip", entries);
 For list-shaped input or when the map key should not be the member name, each child can provide explicit fields:
 
 ```uce
-DTree item;
+DValue item;
 item["name"] = "data/value.txt";
 item["content"] = "42";
 entries["ignored-key"] = item;