distutils docs: Fix a typo (GH-470)

instanciated -> instantiated
diff --git a/Doc/distutils/examples.rst b/Doc/distutils/examples.rst
index 1f5be9c..4e2761d 100644
--- a/Doc/distutils/examples.rst
+++ b/Doc/distutils/examples.rst
@@ -321,7 +321,7 @@
     >>> metadata.description
     'Easily download, build, install, upgrade, and uninstall Python packages'
 
-Notice that the class can also be instanciated with a metadata file path to
+Notice that the class can also be instantiated with a metadata file path to
 loads its values::
 
     >>> pkg_info_path = 'distribute-0.6.8-py2.7.egg-info'