Drop redundant master_doc setting from Sphinx conf

The master_doc option to Sphinx already defaults to looking for a
document named "index" so it's unnecessary to set explicitly in our
case. Clean it up.

diff --git a/doc/source/conf.py b/doc/source/conf.py
index d0f203a..61d1276 100755 (executable)
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -39,6 +39,5 @@ html_title = 'mudpy'
 htmlhelp_basename = '%sdoc' % project
 latex_documents = [(
     'index', '%s.tex' % project, '%s' % project, 'Jeremy Stanley', 'manual')]
-master_doc = 'index'
 pygments_style = 'sphinx'
 source_suffix = '.rst'