remove the wrong directive in Nginx example (#62)

* remove L50-51

* delete these lines:

# This is for local dev only, please do not add this in any production env.
        lua_code_cache off;

* delete these lines in README.md

    server {
        listen 8080;
diff --git a/README.md b/README.md
index 7edf1da..d3f180a 100644
--- a/README.md
+++ b/README.md
@@ -39,8 +39,7 @@
         require("skywalking.client"):startBackendTimer("http://127.0.0.1:8080")
     }
 
-    server {
-        listen 8080;
+
 
         location /ingress {
             default_type text/html;
diff --git a/examples/nginx.conf b/examples/nginx.conf
index c3a7d41..0039bc8 100644
--- a/examples/nginx.conf
+++ b/examples/nginx.conf
@@ -47,11 +47,9 @@
         -- require("skywalking.client"):destroyBackendTimer()
     }
 
-    server {
-        listen 8080;
 
-        # This is for local dev only, please do not add this in any production env.
-        lua_code_cache off;
+
+
 
         location /ingress {
             default_type text/html;