docs: Improve the description for the clear cache option (#7725)

Author: theofidry

src/Console/ConsoleApplication.php

@@ -142,7 +142,7 @@ private function addCustomOptions(InputDefinition $inputDefinition): void
             Option::CLEAR_CACHE,
             null,
             InputOption::VALUE_NONE,
-            'Clear cache'
+            'Clear cache before starting the execution of the command'
         ));
     }