fix: typo in setPlainPassword (#1712)

Author: PawelSuwinski

core/user.md

@@ -106,9 +106,9 @@ class User implements UserInterface, PasswordAuthenticatedUserInterface
         return $this->plainPassword;
     }
 
-    public function setPlainPassword(?string $painPassword): self
+    public function setPlainPassword(?string $plainPassword): self
     {
-        $this->plainPassword = $painPassword;
+        $this->plainPassword = $plainPassword;
 
         return $this;
     }