Update README.md [ci skip]

Author: sergeyklay

README.md

@@ -7,6 +7,10 @@ The Zephir Parser delivered as a C extension for the PHP language.
 
 Supported PHP versions: **5.5**, **5.6**, **7.0**, **7.1**, **7.2**
 
+**NOTE:** The `development` branch will always contain the latest **unstable** version.
+If you wish to check older versions or formal, tagged release, please switch to the relevant
+[branch](https://github.com/phalcon/php-zephir-parser/branches)/[tag](https://github.com/phalcon/php-zephir-parser/tags).
+
 ## Get Started
 
 ### Windows