Point to rbenv and nodenv from setup script

Show the appropriate links when the Ruby and Node dependencies are not
met. This will make it easier for newcomers to install them.

script/setup

@@ -18,13 +18,13 @@ DB_PASSWORD='f00d'
 
 # Check ruby version
 if ! ruby --version | grep $RUBY_VERSION > /dev/null; then
-  printf "${RED}Open Food Network requires ruby ${RUBY_VERSION}${NO_COLOR}\n"
+  printf "${RED}Open Food Network requires ruby ${RUBY_VERSION}${NO_COLOR}. Have a look at: https://github.com/rbenv/rbenv\n"
   exit 1
 fi
 
 # Check node version
 if ! node --version | grep $NODE_VERSION > /dev/null; then
-  printf "${RED}Open Food Network requires node ${NODE_VERSION}${NO_COLOR}\n"
+  printf "${RED}Open Food Network requires node ${NODE_VERSION}${NO_COLOR}. Have a look at: https://github.com/nodenv/nodenv\n"
 fi
 
 # Check postgresql version