Update taxonomy.json

taxonomy.json

@@ -253,8 +253,11 @@
             {"name": "Poetry Generation"},
             {"name": "Text Style Transfer"},
             {"name": "Text Simplification"},
-            {"name": "Data-to-Text Generation"},
-            {"name": "Table-to-Text Generation"},
+            {"name": "Data-to-Text Generation",
+            "children": [
+                {"name": "Table-to-Text Generation"}
+                ]
+            },
             {"name": "Context-to-Text Generation"},
             {"name": "Conditional Text Generation"}
            ]