Add 'empty' builds directory per the wiki. (The folder is not actually empty as it includes a .gitignore.)
diff --git a/builds/.gitignore b/builds/.gitignore
new file mode 100644
index 0000000..5e7d273
--- /dev/null
+++ b/builds/.gitignore
@@ -0,0 +1,4 @@
+# Ignore everything in this directory
+*
+# Except this file
+!.gitignore