Add info about versions and missing tests in README

Author: codeliner

README.md

@@ -10,6 +10,12 @@ Generate Immutable Objects with ease!
 composer require event-engine/php-data
 ```
 
+## Versions
+- 1.x uses method return type hints to detect ImmutableRecord property types
+    - Use this version in PHP 7.2 - PHP 7.3 environments
+- 2.x makes use of PHP 7.4 property type hints 
+    - Use this version in  >= PHP 7.4 environments
+    
 ## PHPStorm Templates
 
 The `EventEngine\Data` package contains a set of live templates specifically designed to work together with the `EventEngine\Data\ImmutableRecord`. 
@@ -22,3 +28,9 @@ Please find the `settings.zip` [here](https://github.com/event-engine/php-data/b
 ## Usage
 
 Usage is described in the [documentation](https://event-engine.io/api/immutable_state.html)
+
+## No Tests?
+
+Looks strange, right? A stable open source package without a single test can only be a joke ... 
+You're right! The situation isn't ideal. However, this is a low level package used by [event-engine/php-json-schema](https://github.com/event-engine/php-json-schema).
+The tests included there also cover the implementation of this package. Anyway, a pull request that adds some tests is always welcome!