Update build.sh

Edit response condition

Author: zhuje

scripts/build-image.sh

@@ -43,7 +43,7 @@ echo_vars
 
 # Prompt use it check env vars before proceeding to build 
 read -r -p "Are the environmental variables correct [y/N] " response
-if [[ "$response" =~ ^([nN][oO])$ ]]
+if [[ "${response:0:1}" =~ ^([nN])$ ]]
 then
     exit 0
 fi