Fix the warning type `misc.highlighting_failure` does not work

CHANGES

@@ -17,6 +17,7 @@ Bugs fixed
 * #3255: In Py3.4 environment, autodoc doesn't support documentation for
   attributes of Enum class correctly.
 * #3261: ``latex_use_parts`` makes sphinx crash
+* The warning type ``misc.highlighting_failure`` does not work
 
 Release 1.5.1 (released Dec 13, 2016)
 =====================================

sphinx/highlighting.py

@@ -144,7 +144,7 @@ class PygmentsBridge(object):
             elif warn:
                 warn('Could not lex literal_block as "%s". '
                      'Highlighting skipped.' % lang,
-                     type='misc', subtype='higlighting_failure')
+                     type='misc', subtype='highlighting_failure')
             else:
                 raise exc
             hlsource = highlight(source, lexers['none'], formatter)