Add doc directory to gitignore
diff --git a/.gitignore b/.gitignore
index 2feef80..c400a9a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -69,4 +69,5 @@
 **/_site/
 **/_*
 **/_*/
-results/
\ No newline at end of file
+results/
+doc/
\ No newline at end of file