Frontend nginx should almost always return index.html (#2390)

* Frontend nginx should almost always return index.html

### What's done:
 * Fixed nginx.conf

save-frontend/nginx.conf

@@ -154,16 +154,6 @@ http {
     # Directory where static files are located
     root /workspace/static;
 
-    location / {
-      # Specify files sent to client if specific file not requested (e.g.
-      # GET www.example.com/). NGINX sends first existing file in the list.
-      index index.html index.htm Default.htm;
-      add_header Cache-Control "private; no-store";
-      etag off;
-      add_header Last-Modified "";
-      if_modified_since off;
-    }
-
     location ~* \.(html)$ {
       add_header Cache-Control "private; no-store";
       etag off;
@@ -187,5 +177,15 @@ http {
       deny all;
       return 404;
     }
+
+    location / {
+      # Specify files sent to client if specific file not requested (e.g.
+      # GET www.example.com/). NGINX sends first existing file in the list.
+      index /index.html index.html index.htm Default.htm;
+      add_header Cache-Control "private; no-store";
+      etag off;
+      add_header Last-Modified "";
+      if_modified_since off;
+    }
   }
 }