add templateParts theme.json data

seedlet-blocks/experimental-theme.json

@@ -1,4 +1,12 @@
 {
+	"templateParts": {
+		"header": {
+			"section": "header"
+		},
+		"footer": {
+			"section": "footer"
+		}
+	},
 	"global": {
 		"presets": {
 			"font-size": [