remove language zh_CN to speed sphinx doc build

source/conf.py

@@ -67,7 +67,7 @@
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
 #language = None
-language = 'zh_CN'
+#language = 'zh_CN'
 #html_search_language = 'zh'
 
 # List of patterns, relative to source directory, that match files and