Add phpdoc

Author: yannoff

src/Phar.php

@@ -17,7 +17,15 @@
 
 use Phar as BuiltinPhar;
 
-function php_strip_whitespace($file): string
+/**
+ * Replacement for the `php_strip_whitespace()` native method,
+ * which mistakenly treat php attributes as bash-like comments
+ *
+ * @param string $file
+ *
+ * @return string
+ */
+function php_strip_whitespace(string $file): string
 {
     $lines = file($file, FILE_IGNORE_NEW_LINES);