Fix missing $

Author: jderusse

lock.rst

@@ -273,7 +273,7 @@ type-hinting it with :class:`Symfony\\Component\\Lock\\LockInterface`.
 Symfony also provide a corresponding factory and store following the same rules
 (e.g. ``invoice`` generates a ``lock.invoice.factory`` and
 ``lock.invoice.store``, both can be injected automatically by naming
-respectively ``$invoiceLockFactory`` and ``invoiceLockStore`` and type-hinted
+respectively ``$invoiceLockFactory`` and ``$invoiceLockStore`` and type-hinted
 with :class:`Symfony\\Component\\Lock\\LockFactory` and
 :class:`Symfony\\Component\\Lock\\PersistingStoreInterface`)