Fix markup in generics specification

Author: Viicos

docs/spec/generics.rst

@@ -97,7 +97,7 @@ There are several ways to define a user-defined class as generic:
 
 * Include a ``Generic`` base class.
 * Use the new generic class syntax in Python 3.12 and higher.
-* Include a `` Protocol`` base class parameterized with type variables. This
+* Include a ``Protocol`` base class parameterized with type variables. This
   approach also marks the class as a protocol - see
   :ref:`generic protocols<generic-protocols>` for more information.
 * Include a generic base class parameterized with type variables.