Renamed README.txt with README.md

Closes #3317563

README.md

-CONTENTS OF THIS FILE
----------------------
+# KEY AUTH
 
  * Introduction
  * Installation
@@ -8,8 +7,7 @@ CONTENTS OF THIS FILE
  * Maintainers
 
 
-INTRODUCTION
-------------
+## Introduction
 
 Key auth provides simple key-based authentication on a per-user
 basis similar to basic_auth but without requiring
@@ -22,24 +20,21 @@ For a full description of the module, visit the project page:
 https://www.drupal.org/project/key_auth
 
 
-INSTALLATION
-------------
+## Installation
 
  * Run composer to install the dependencies.
-   composer require 'drupal/key_auth:^1.0'
+   `composer require 'drupal/key_auth:^1.0'`
 
  * Install as you would normally install a contributed Drupal module.
-   See: https://www.drupal.org/docs/8/extending-drupal-8
+   See: <https://www.drupal.org/docs/8/extending-drupal-8>
    /installing-drupal-8-modules for further information.
 
  * A more comprehensive installation instruction for
-   Drupal 8 can be found at https://www.drupal.org/node/2923804/
+   Drupal 8 can be found at <https://www.drupal.org/node/2923804/>
 
 
-SETUP & USAGE
--------------
+## Setup & Usage
 
- * Remove View published content permission from role, you are using this module for.
  * Grant users the 'Use key authentication' permission.
  * Configure the basic settings at admin/config/services/key-auth.
  * Users with adequate permissions can view/update/delete their key at
@@ -47,23 +42,15 @@ SETUP & USAGE
  * To use with core rest, enable the key_auth authentication provider for your
    endpoints of choice.
  * To use with jsonapi, no additional configuration is required.
- * To use for route authentication, 'key_auth' must be specified as an '_auth'
-   option for the route. E.g.:
-     options:
-       _auth: ['key_auth']
-   See https://www.drupal.org/docs/8/api/authentication-api/overview for details.
  * If Header detection is enabled, pass in a header with the name chosen in the
    configuration, and a value of your user's key
-   (ie, api-key: b9a9a0ee50ceab7191282b51c).
+   (ie, `api-key: b9a9a0ee50ceab7191282b51c`).
  * If Query detection is enabled, include a query parameter in the endpoint URL
    with the name chosen in the configuration, and a value of your user's key
-   (ie, ?api-key=b9a9a0ee50ceab7191282b51c).
+   (ie, ?`api-key=b9a9a0ee50ceab7191282b51c`).
 
-Please Note:
-To deny the anonymous user role access to a REST endpoint, one need to change permissions and deny the anonymous user the permission "View published content". Then one can enable this module and use Key authentication (as an alternative to Basic authentication) to get access to the endpoint.
 
-SUPPORT REQUESTS
-----------------
+## Support requests
 
 Before posting a support request, carefully read the installation
 instructions provided in module documentation page.
@@ -72,15 +59,14 @@ Before posting a support request, check Recent log entries at
 admin/reports/dblog
 
 Once you have done this, you can post a support request at module issue queue:
-https://www.drupal.org/project/issues/key_auth
+<https://www.drupal.org/project/issues/key_auth>
 
 When posting a support request, please inform if you were able to see any errors
 in Recent log entries.
 
 
-MAINTAINERS
------------
+## Maintainers
 
 Current maintainers:
- * mstef - https://www.drupal.org/u/mstef
- * rajeshreeputra - https://www.drupal.org/u/rajeshreeputra
+ - mstef (mstef) - <https://www.drupal.org/u/mstef>
+ - rajeshreeputra (rajeshreeputra) - <https://www.drupal.org/u/rajeshreeputra>