Update release notes

RELEASENOTES.md

@@ -4,16 +4,28 @@ For more information and documentation for administrators, users and developers
 
 ## Joomla and PHP Compatibility
 
-Akeeba Social Login is compatible with Joomla! 3.4, 3.5, 3.6, 3.7 and 3.8. It requires PHP 5.3.10 or later, the same minimum PHP version as Joomla! itself. It's also compatible with PHP 5.4, 5.5, 5.6, 7.0 and 7.1.
+Akeeba Social Login is compatible with Joomla! 3.4, 3.5, 3.6, 3.7 and 3.8. Preliminary support for Joomla! 4.0 Alpha 2 is included in this version. See notes. It requires PHP 5.3.10 or later, the same minimum PHP version as Joomla! itself. It's also compatible with PHP 5.4, 5.5, 5.6, 7.0 and 7.1.
 
 We strongly recommend using the latest published Joomla! version and PHP 7.0 or 7.1 later _for optimal security of your site_.
 
+### Preliminary Joomla! 4 support
+
+Joomla! 4 is still in its very early development stages. While this version of SocialLogin has added preliminary support for Joomla! 4.0 Alpha 2 we cannot guarantee that it will work in any future release of Joomla! 4, be it development or stable. We reserve the right to remove Joomla! 4 compatibility and / or delegate this feature to a future version of our software.
+
 ## Language files
 
 Akeeba SocialLogin comes with English (Great Britain) language built-in. Installation packages for other languages are available [on our language download page](https://cdn.akeebabackup.com/language/sociallogin/index.html).
 
 ## Changelog
 
+# 2.0.0
+
+**New features**
+
+* Compatible with Joomla! 3.4 to 3.8 (inclusive) and, now, also Joomla! 4.0.
+
 **Bug fixes**
 
-* gh-15 Twitter and Google plugins are not installed
+* gh-16 The buttons should not appear in the back-end of the site by default 
+* gh-24 Validated user accounts still result in Joomla! email validation email being sent  
+* Fatal error displaying the site's error page