Fix typo pointed out on docs@ by Yaniv Sayeh

Doc/library/copyreg.rst

@@ -9,7 +9,7 @@
    module: pickle
    module: copy
 
-The :mod:`copyreg` module offers a way to define fuctions used while pickling
+The :mod:`copyreg` module offers a way to define functions used while pickling
 specific objects.  The :mod:`pickle` and :mod:`copy` modules use those functions
 when pickling/copying those objects.  The module provides configuration
 information about object constructors which are not classes.