Add nginx file so that the docker container will serve the files

frontend/nginx/nginx.conf

@@ -0,0 +1,13 @@
+server {
+    listen 80;
+
+    location / {
+        root   /usr/share/nginx/html;
+        index  index.html index.htm;
+        # to redirect all the requests to index.html, 
+        # useful when you are using react-router
+        try_files $uri /index.html; 
+    }
+
+    error_page   500 502 503 504  /50x.html;
+}