docs: add notice that support for end-of-life PHP versions will be dr…

…opped in 2024

CHANGELOG.md

@@ -5,6 +5,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 
+## [Unreleased]
+### Changed
+* Added notice in Readme that starting in 2024 the library will drop support for PHP versions that are officially end-of-life.
+
+
 ## [1.5.1] - 2023-09-11
 ### Fixed
 * Add `.gitattributes` file to exclude irrelevant files from package download.
@@ -114,6 +119,7 @@ Stable release.
 Initial version.
 
 
+[Unreleased]: https://github.com/DeepLcom/deepl-php/compare/v1.5.1...HEAD
 [1.5.1]: https://github.com/DeepLcom/deepl-php/compare/v1.5.0...v1.5.1
 [1.5.0]: https://github.com/DeepLcom/deepl-php/compare/v1.4.0...v1.5.0
 [1.4.0]: https://github.com/DeepLcom/deepl-php/compare/v1.3.0...v1.4.0

README.md

@@ -35,6 +35,11 @@ composer require deeplcom/deepl-php
 
 The library officially supports PHP 7.3 and later.
 
+Starting in 2024, we will drop support for older PHP versions that have reached
+official end-of-life. You can find the PHP versions and support timelines 
+[here][php-version-list].
+To continue using this library, you should update to PHP 8.1+.
+
 ## Usage
 
 Construct a `Translator` object. The first argument is a string containing your
@@ -536,6 +541,8 @@ environment variables defined referring to the mock-server.
 
 [issues]: https://www.github.com/DeepLcom/deepl-php/issues
 
+[php-version-list]: https://www.php.net/supported-versions.php
+
 [pro-account]: https://www.deepl.com/pro-account/?utm_source=github&utm_medium=github-php-readme
 
 [PSR-3-logger]: http://www.php-fig.org/psr/psr-3/