docs: more formatting fixes

Change-Id: I51aa4ee162d11f5154919d4a4a3aa988ac128e33
diff --git a/docs/conf.py b/docs/conf.py
index 6de14ad..5484143 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -47,7 +47,7 @@
 
 addExtensionIfExists('sphinxcontrib.doxylink')
 
-exclude_patterns = ['Thumbs.db', '.DS_Store']
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
 # Disable syntax highlighting of code blocks by default.
 highlight_language = 'none'
@@ -61,7 +61,6 @@
 
 html_theme = 'furo'
 html_logo = 'ndn-logo.svg'
-html_last_updated_fmt = ''
 html_copy_source = False
 html_show_sourcelink = False