disable smart quotes in sphinx to workaround a spellchecker issue (#3946)

This makes it so we don't have to pin sphinx while we wait for
sphinxcontrib-spelling to properly handle smart quotes
diff --git a/docs/docutils.conf b/docs/docutils.conf
new file mode 100644
index 0000000..e0c3d47
--- /dev/null
+++ b/docs/docutils.conf
@@ -0,0 +1,2 @@
+[parsers]
+smart_quotes: no