update nginx config

Dockerfile

@@ -18,7 +18,7 @@ server {\n\
     index index.html index.htm;\n\
 \n\
     location / {\n\
-    try_files \$uri \$uri/ =404;\n\
+    try_files \$uri \$uri/ /index.html;\n\
     }\n\
 }\n\
 " > /etc/nginx/conf.d/default.conf