Prepare release for 3.0.0 (#20)

* Add CHANGELOG
* Update README

Author: szhajdu

CHANGELOG-3.0.md

@@ -0,0 +1,11 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [3.0.0] - 2022-03-08
+### Added
+- PHP 8 support.
+### Removed
+- Drop PHP 7 support.

README.md

@@ -11,8 +11,8 @@ Inspiration comes from [herloct/codeception-slim-module](https://github.com/herl
 ## Install
 
 ### Minimal requirements
-- php: `^7.2`
-- slim/slim: `^4.2`
+- php: `^8.0`
+- slim/slim: `^4.7`
 - codeception/codeception: `^4.0`
 
 If you don't know Codeception, please check [Quickstart Guide](https://codeception.com/quickstart) first.
@@ -24,6 +24,12 @@ you can add codeception-slim-module with a single composer command.
 composer require --dev docler-labs/codeception-slim-module
 ```
 
+For PHP 7 support, please use `docler-labs/codeception-slim-module:^2.0` version
+
+```shell
+composer require --dev docler-labs/codeception-slim-module "^2.0"
+```
+
 If you use Slim v3, please use the previous version from library:
 
 ```shell