update redirect for versioned api

Author: Chris Cho

config/redirects

@@ -5,4 +5,4 @@ define: versions v1.1 v1.2 v1.3 v1.4 v1.5 v1.6 v1.7 v1.8 v1.9 v1.10 master
 symlink: upcoming -> master
 symlink: current -> v1.10
 
-[v1.8-master]: ${prefix}/${version}/tutorials/versioned-api/ -> ${base}/${version}/tutorials/stable-api/
+[v1.9-master]: ${prefix}/${version}/tutorials/versioned-api/ -> ${base}/${version}/tutorials/stable-api/