Fix rst in igbinary in the cache documentation

Author: alexander-schranz

components/cache/adapters/redis_adapter.rst

@@ -305,7 +305,7 @@ Encrypts cached data using Sodium for enhanced security::
 DefaultMarshaller with igbinary Serialization
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Uses ``igbinary` for faster and more efficient serialization when available::
+Uses ``igbinary`` for faster and more efficient serialization when available::
 
     $marshaller = new DefaultMarshaller(true);