chore: tweaks

Author: technote-space

README.ja.md

@@ -13,6 +13,8 @@
 
 [デモ](https://technote-space.github.io/jquery.marker-animation/)
 
+## Table of Contents
+
 <!-- START doctoc generated TOC please keep comment here to allow auto update -->
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 <details>

README.md

@@ -13,6 +13,8 @@ jQuery plugin to add under line animation like highlighter.
 
 [Demonstration](https://technote-space.github.io/jquery.marker-animation/)
 
+## Table of Contents
+
 <!-- START doctoc generated TOC please keep comment here to allow auto update -->
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 <details>