Issue #3404818 by rksyravi: Replace README.txt with README.md

Closes #3404818

README.md

-CONTENTS OF THIS FILE
-=====================
+## CONTENTS OF THIS FILE
 
- * Introduction
- * Requirements
- * Installation
- * Configuration
- * Maintainers
+ - Introduction
+ - Requirements
+ - Installation
+ - Configuration
+ - Maintainers
 
 
-INTRODUCTION
-============
+## INTRODUCTION
 
 Lock Layout Builder module provides the locking mechanism to discourage
 concurrent editing of Node layout pages.
@@ -21,30 +19,26 @@ concurrent editing of Node layout pages.
    https://www.drupal.org/project/issues/lock_layout_builder
 
 
-REQUIREMENTS
-============
+## REQUIREMENTS
 
 This module requires the following core and module:
 
  * Layout Builder (Drupal core >= 8.7.7)
- * Content locking (anti-concurrent editing) (https://www.drupal.org/project/content_lock)
+ * [Content locking (anti-concurrent editing)](https://www.drupal.org/project/content_lock)
 
 
-INSTALLATION
-============
+## INSTALLATION
 
  * Install as you would normally install a contributed Drupal module. Visit
    https://www.drupal.org/node/1897420 for further information.
 
 
-CONFIGURATION
-=============
+## CONFIGURATION
 
  * No extra configuration is needed.
 
 
-MAINTAINERS
-===========
+## MAINTAINERS
 
 Current maintainers:
-* Ravi Kumar Singh (rksyravi) (https://www.drupal.org/u/rksyravi)
+* Ravi Kumar Singh [rksyravi](https://www.drupal.org/u/rksyravi)