Update template for newest Sphinx.
diff --git a/Doc/conf.py b/Doc/conf.py
index 6cf6433..45d40fb 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -74,9 +74,6 @@
 # typographically correct entities.
 html_use_smartypants = True
 
-# Content template for the index page, filename relative to this file.
-html_index = 'indexcontent.html'
-
 # Custom sidebar templates, filenames relative to this file.
 html_sidebars = {
     'index': 'indexsidebar.html',
@@ -85,6 +82,7 @@
 # Additional templates that should be rendered to pages.
 html_additional_pages = {
     'download': 'download.html',
+    'index': 'indexcontent.html',
 }
 
 # Output file base name for HTML help builder.