more README tweaks.

README.markdown

@@ -106,6 +106,32 @@ Example Config
         }
     }
 
+Description
+===========
+
+This module embeds the Lua interpreter into the nginx core and intergrades the powerful Lua threads (aka Lua coroutines) into the nginx event model
+by means of nginx subrequests.
+
+Unlike Apache's mod_lua and Lighttpd's mod_magnet, this module can be 100% non-blocking on network traffic
+as long as you use the `ngx.location.capture` interface
+to let the nginx core to do all your
+requests to mysql, postgresql, memcached,
+upstream http web services, and etc etc etc (see
+ngx_drizzle, ngx_postgres, ngx_memc, and ngx_proxy modules for details).
+
+The Lua interpreter instance is shared across all
+the requests in a single nginx worker process.
+
+Request contexts are isolated from each other
+by means of Lua (light) threads (aka Lua coroutines). And Lua modules loaded are persistent on
+the nginx worker process level. So the memory
+footprint is very small even when your
+nginx worker process is handling 10K requests.
+
+We're already using this module very heavily
+in our production web applications here in
+Taobao.com, Alibaba Group.
+
 Directives
 ==========