Merge pull request sphinx-contrib#217 from adamchainz/patch-2

Fix spelling:word-list example

Author: dhellmann

docs/source/customize.rst

@@ -155,7 +155,7 @@ can be added to the list of known words for just that document.
 
 ::
 
-  .. spelling::
+  .. spelling:word-list::
 
      Docutils
      Goodger