Update README.md

Author: zm-l

docs/README.md

@@ -3,6 +3,16 @@
 
 Shinsoo is a desktop app for task management, optimized for use via a Command Line Interface (CLI) while still having the benefits of a Graphical User Interface (GUI). If you can type fast, Shinsoo can get your task management done faster than traditional GUI apps.
 
+- [Quick Start](#quick-start)
+* [Features](#features)
+  - [Feature - Add Tasks](#feature---add-tasks)
+  - [Feature - List](#feature---list)
+  - [Feature - Find](#feature---find)
+  - [Feature - Marking](#feature---marking)
+  - [Feature - Delete](#feature---delete)
+  - [Feature - Exit](#feature---exit)
++ [Command Summary](#command-summary)
+
 ## Quick Start
 1. Ensure you have Java 11 or above installed in your Computer.
 2. Download the latest addressbook.jar from here.
@@ -64,7 +74,7 @@ Examples: <br/>
 ---
 ### Feature - Marking
 
-Deletes a task from the app.
+Marks a task from the app.
 
 Format: <br/>
 `mark INDEX` <br/>