add: template editor

src/components/MarkdownTemplate/LayoutEditor.js

@@ -0,0 +1,16 @@
+import React, {useState} from 'react';
+const LayoutEditor = ({layout, onChange}) => {
+    const [_layout, setLayout] = useState(layout || "");
+    return (
+        <textarea
+            className="textarea"
+            value={_layout}
+            onChange={(e) => {
+                setLayout(e.target.value);
+                onChange(layout);
+            }}
+        />
+    );
+};
+
+export default LayoutEditor;