Updated README.txt to README.md

Updated README.txt to README.md as per Drupal markdown practices. Please review the same.

README.md

-CONTENTS OF THIS FILE
----------------------
+# Image Annotator [Annotorious] Module
 
- * Introduction
- * Requirements
- * Installation
- * Configuration
- * Maintainers
+## Contents Of This File
 
+ - Introduction
+ - Requirements
+ - Installation
+ - Configuration
+ - Maintainers
 
-INTRODUCTION
-------------
 
-Image Annotator module allows users to create annotations on node images.
+## Introduction
 
-Users can highlight a particular portion of a node's image
-by drawing a rectangle over the image and adding a note to it.
+- Image Annotator module allows users to create annotations on node images.
 
-Adding, deleting, updating and viewing of these annotations can easily
-be controlled by permission configuration.
+- Users can highlight a particular portion of a node's image
+  by drawing a rectangle over the image and adding a note to it.
 
-It also supports multi-valued image fields.
+- Adding, deleting, updating and viewing of these annotations can easily
+  be controlled by permission configuration.
 
+- It also supports multi-valued image fields.
 
-REQUIREMENTS
-------------
 
-This module requires the following modules:
- * Image (Core)
- * Node (Core)
+## Requirements
 
-This module requires the Annotorious library:
-https://github.com/annotorious/annotorious
+- This module requires the following modules:
+  -  Image (Core)
+  -  Node (Core)
 
-Manual installation:
- * Download the library from:
+- This module requires the Annotorious library:
+   https://github.com/annotorious/annotorious
+
+- Manual installation:
+  - Download the library from:
    https://github.com/annotorious/annotorious/releases/tag/v0.6.4
- * Extract it in your 'libraries' folder, file paths should be:
-   - DRUPAL_ROOT/libraries/annotorious/annotorious.min.js
-   - DRUPAL_ROOT/libraries/annotorious/css/annotorious.css
-   - DRUPAL_ROOT/libraries/annotorious/css/theme-dark/annotorious-dark.css
+  - Extract it in your '`libraries`' folder, file paths should be:
+   - `DRUPAL_ROOT/libraries/annotorious/annotorious.min.js`
+   - `DRUPAL_ROOT/libraries/annotorious/css/annotorious.css`
+   - `DRUPAL_ROOT/libraries/annotorious/css/theme-dark/annotorious-dark.css`
 
-Composer installation:
+**Composer installation:**
 
 1: Ensure that you have the `oomphinc/composer-installers-extender` package
    installed.
-2: Add an "installer-types" section in the "extra" of your project composer.json
-   file, make sure you have "bower-asset" and "npm-asset" listed.
+   
+2: Add an "`installer-types`" section in the "`extra`" of your project composer.json
+   file, make sure you have "`bower-asset`" and "`npm-asset`" listed.
+  ```
    For example:
      "installer-types": [
          "bower-asset",
          "npm-asset"
      ],
-3: In the "installer-paths" section in the "extra" of your project composer.json
+```
+3: In the "`installer-paths`" section in the "`extra`" of your project composer.json
  file, ensure you have the types drupal-library, bower-asset, and npm-asset.
+ ```
    For example:
      "web/libraries/{$name}": [
          "type:drupal-library",
          "type:bower-asset",
          "type:npm-asset"
      ],
+```
 4: Add https://asset-packagist.org defined in your Composer repositories.
+```
    For example:
     "repositories": {
         "asset-packagist": {
             "type": "composer",
             "url": "https://asset-packagist.org"
         },
-        ...
-5: Run 'composer require npm-asset/annotorious:0.6.4'.
+```
+
+5: Run '`composer require npm-asset/annotorious:0.6.4`'.
 
 
-INSTALLATION
-------------
+## Installation
 
- * Install as you would normally install a contributed drupal module. See:
-   https://drupal.org/documentation/install/modules-themes/modules-8
+ - Install as you would normally install a contributed drupal module. See:
+   [Installing Modules](https://www.drupal.org/docs/extending-drupal/installing-modules)
    for further information.
 
 
-CONFIGURATION
--------------
+## Configuration
 
- * Enable the Image Annotator module on your site.
- * Go to the configuration pages (admin/config/img_annotator) and choose
-   your settings.
- * Go on a node's page with an image field with annotations enabled.
- * If you have the appropriate permissions you will be able to draw annotations.
+ - Enable the Image Annotator module on your site.
+ - Go to the configuration pages (`admin/config/img_annotator`) and choose
+ - your settings.
+ - Go on a node's page with an image field with annotations enabled.
+ - If you have the appropriate permissions you will be able to draw annotations.
 
 
-MAINTAINERS
------------
+## Maintainers
 
 Current maintainers:
- * Florent Torregrosa (Grimreaper) - https://www.drupal.org/user/2388214
+ - Florent Torregrosa (Grimreaper) - https://www.drupal.org/user/2388214
 
 Previous maintainers:
- * abhaysaraf - https://www.drupal.org/user/2723079
+ - abhaysaraf - https://www.drupal.org/user/2723079
 
 This project has been sponsored by:
- * Smile - https://www.drupal.org/smile
+ - [Smile](https://www.drupal.org/smile)
    Sponsored maintenance.