Fix u2f with nginx rp

docs/first_steps.md

@@ -83,6 +83,7 @@ HTTP_PORT=8080
 HTTPS_PORT=127.0.0.1
 HTTPS_PORT=8443
 ```
+** IMPORTANT: Do not use port 8081 **
 
 Recreate affected containers by running `docker-compose up -d`.
 
@@ -125,6 +126,7 @@ server {
     location / {
         proxy_pass http://127.0.0.1:8080/;
         proxy_redirect http://127.0.0.1:8080/ $scheme://$host:$server_port/;
+        proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header X-Forwarded-Proto $scheme;