access index but return 404 not Found

[khxkhx321]

hi:
I tried to run this application on my computer. I installed redis, Openresty and modify the nginx.conf.
Now when I access to localhost/about I got the right result.
Howerver when I access to localhost/index nginx just return 404 not found. Can you help me?
I found "-- use nginx $root variable for template dir, needs trailing slash
TEMPLATEDIR = ngx.var.root .. 'lua/';
-- The git repository storing the markdown files. Needs trailing slash
BLAGDIR = TEMPLATEDIR .. 'md/'" in the file index.lua but I don't konw what files include in the two dir.Does this lead to the 404 error?
Here is my conf:

lua_package_path '/home/khx/lua/?.lua;;';
server {
listen 80;
server_name localhost;
set $root /home/khx/;
root $root;
#charset koi8-r;

    #access_log  logs/host.access.log  main;
# Serve static if file exist, or send to lua
    location / { try_files $uri @lua; }
    # Lua app
    location @lua {
    default_type 'text/plain'; 
        content_by_lua_file $root/lua/index.lua;
    }
    #location / {
    #    root   html;
    #    index  index.html index.htm;
    #}
location /hello { 
      default_type 'text/plain'; 
      content_by_lua 'ngx.say("hello, lua")'; 
}

    #error_page  404              /404.html;

[khxkhx321]

It's my fault.I didn't read the source code carefully! Now the problem is solved. To access to index page, page should be localhost/ and without "index" at back. I have another question: How the structure of the project look like. Where should I put markdown files or other static files like .js or .jpg. What is the redis databases structure for this project.