add robots.txt to src
diff --git a/static/robots.txt b/static/robots.txt
new file mode 100644
index 0000000..c630a83
--- /dev/null
+++ b/static/robots.txt
@@ -0,0 +1,16 @@
+# robots.txt for https://druid.apache.org
+
+# Keep robots from crawling old Druid doc versions
+
+User-agent: *
+Disallow: /docs/0*/
+Disallow: /docs/1*/
+Disallow: /docs/2*/
+Disallow: /docs/3*/
+Disallow: /docs/4*/
+Disallow: /docs/5*/
+Disallow: /docs/6*/
+Disallow: /docs/7*/
+Disallow: /docs/8*/
+Disallow: /docs/9*/
+