Drop the (only) use of the bibtex extension

Change-Id: I78acb4f58a27b5bb03d9cccf1314813de663103e
diff --git a/conf.py b/conf.py
index 036520a..e3685b2 100644
--- a/conf.py
+++ b/conf.py
@@ -36,9 +36,7 @@
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = [
-    'sphinxcontrib.bibtex',
-]
+extensions = []
 
 # The master toctree document.
 master_doc = 'index'
@@ -51,8 +49,6 @@
 # This pattern also affects html_static_path and html_extra_path.
 exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
 
-bibtex_bibfiles = ['refs.bib']
-
 
 # -- Options for HTML output -------------------------------------------------