Updated README.txt to README.md as per Drupal Standards

Closes #3315952

README.md

+CONTENTS OF THIS FILE
+---------------------
+
+-   Introduction
+-   Requirements
+-   Recommended Modules
+-   Installation
+-   Configuration
+
+INTRODUCTION
+------------
+
+After a given timeout has passed, users are given a configurable session
+expiration prompt. They can reset the timeout, logout, or ignore it, in
+which case they'll be logged out after the padding time is elapsed. This
+is all backed up by a server side logout if JS is disabled or bypassed.
+
+REQUIREMENTS
+------------
+
+None.
+
+RECOMMENDED MODULES
+-------------------
+
+-   Session Limit (https://www.drupal.org/project/session\_limit)
+-   Password Policy (https://www.drupal.org/project/password\_policy)
+
+INSTALLATION
+------------
+
+-   Install as usual: See
+    https://www.drupal.org/documentation/install/modules-themes/modules-8
+    for further information.
+
+CONFIGURATION
+-------------
+
+-   Configure permissions : Home \>\> Administration \>\> People
+    (/admin/people/permissions)
+-   Configure Automated logout : Home \>\> Administration \>\>
+    Configuration \>\> People (/admin/config/people/autologout)
+-   Configurable "Global timeout" and "Timeout padding". The latter
+    determines how much time a user has to respond to the prompt and
+    when the server side timeout will occur.
+-   Configurable messaging.
+-   Configurable "Redirect URL" with the destination automatically
+    appended.
+-   Configure which roles will be automatically logged out.
+-   Configure if a logout will occur on admin pages.
+-   Integration with ui.dialog if available. This makes for attractive
+    and more functional dialogs.
+-   Configurable timeout based on user.
+-   Configurable maximum timeout. Primarily used when a user has
+    permission to change their timeout value, this will be a cap or
+    maximum value they can use.
+-   Order of precedence is : user timeout -\> lowest role timeout -\>
+    global timeout.
+-   So if a user has a user timeout set, that is their timeout
+    threshold, if none is set the lowest timeout value based on all the
+    roles the user belongs to is used, if none is set the global timeout
+    is used.
+-   Make sure the timeout value in seconds is smaller than the value for
+    session.gc\_maxlifetime. Otherwise your session will be destroyed
+    before autologout kicks in.