merge from upstream and update to 6.0.x

Author: dhalbert

docs/robots.txt

@@ -1,6 +1,6 @@
 User-agent: *
 Allow: /*/latest/
 Allow: /en/latest/   # Fallback for bots that don't understand wildcards
-Allow: /*/5.3.x/
-Allow: /en/5.3.x/    # Fallback for bots that don't understand wildcards
+Allow: /*/6.0.x/
+Allow: /en/6.0.x/    # Fallback for bots that don't understand wildcards
 Disallow: /