chore: doc asset

Author: 94noni

components/asset.rst

@@ -211,19 +211,19 @@ every day::
 
     class DateVersionStrategy implements VersionStrategyInterface
     {
-        private $version;
+        private string $version;
 
         public function __construct()
         {
             $this->version = date('Ymd');
         }
 
-        public function getVersion(string $path)
+        public function getVersion(string $path): string
         {
             return $this->version;
         }
 
-        public function applyVersion(string $path)
+        public function applyVersion(string $path): string
         {
             return sprintf('%s?v=%s', $path, $this->getVersion($path));
         }