added some robots to the blocked list

services/web/public/robots.txt

@@ -3,3 +3,16 @@
 User-agent: *
 Disallow: /project/*
 Disallow: /recurly.com
+Allow: /
+
+User-Agent: AhrefsBot
+Disallow: /
+
+User-Agent: XoviBot
+Disallow: /
+
+User-Agent: RankSonicBot
+Disallow: /
+
+User-Agent: SMTBot
+Disallow: /