[TASK] Switch README file to Markdown, adjust dependencies

Author: fsuter

README.md

@@ -0,0 +1,41 @@
+[![Latest Stable Version](https://poser.pugx.org/cobweb/flush_language_cache/v)](https://packagist.org/packages/cobweb/flush_language_cache)
+[![Total Downloads](http://poser.pugx.org/cobweb/flush_language_cache/downloads)](https://packagist.org/packages/cobweb/flush_language_cache)
+[![Monthly Downloads](http://poser.pugx.org/cobweb/flush_language_cache/d/monthly)](https://packagist.org/packages/cobweb/flush_language_cache)
+[![Daily Downloads](http://poser.pugx.org/cobweb/flush_language_cache/d/daily)](https://packagist.org/packages/cobweb/flush_language_cache)
+[![PHP Version Require](http://poser.pugx.org/cobweb/flush_language_cache/require/php)](https://packagist.org/packages/cobweb/flush_language_cache)
+
+# Flush Language Cache
+
+This small TYPO3 CMS extension adds an item to the flush cache menu to allow for
+flushing only the language cache (`l10n`). This way you can avoid flushing the
+whole system cache when updating just a couple of localized strings (in locallang
+files).
+
+This extension requires TYPO3 CMS 11 or more.
+
+Just install it and flush the system cache. Reload the backend and the new
+item will appear in the flush cache menu.
+
+There is also a command-line tool that can be called with:
+
+```text
+path/to/php path/to/bin/typo3 languagecache:flush
+```
+
+## User TSconfig
+
+It is possible to give access to this flush cache option to ordinary backend users
+with the following User TSconfig:
+
+```typoscript
+options.clearCache.flushLanguageCache = 1
+```
+
+## Credits
+
+The icon is based on the following images:
+
+* thunderbolt by H Alberto Gongora from the Noun Project
+* chat bubble by Tereza Moravcová from the Noun Project
+
+Thanks to Dmytro Nozdrin for the TYPO3 9 compatibility update and some code cleanup.

README.rst

@@ -17,8 +17,8 @@
 		}
 	},
 	"require": {
-		"php": ">=7.4.0",
-		"typo3/cms-core": "^11.5 || ^12.0"
+		"php": "^7.4 || ^8.0 || ^8.1 || ^8.2",
+		"typo3/cms-core": "^11.5 || ^12.4"
 	},
 	"replace": {
 		"typo3-ter/flush_language_cache": "self.version"

composer.json

@@ -18,8 +18,8 @@
         'version' => '4.0.0',
         'constraints' => [
                 'depends' => [
-                        'typo3' => '11.5.0-12.9.99',
-                        'php' => '7.4.0-8.1.99'
+                        'typo3' => '11.5.0-12.4.99',
+                        'php' => '7.4.0-8.2.99'
                 ],
                 'conflicts' => [],
                 'suggests' => [],