Add Sphinx Relay opt fragment (#458)

* Add Sphinx Relay opt fragment

* Integrate keysend via existing opt

* Mount lnd datadir readonly

* Update Sphinx Relay and env vars

* Add Sphinx Relay docs

* Update Sphinx Relay

Production/nginx.tmpl

@@ -93,7 +93,17 @@
 		proxy_pass http://btctransmuter;
 	}
 		{{ end }}
-		
+
+  {{ if (eq $serviceName "sphinxrelay") }}
+  location /sphinxrelay/ {
+    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;
+    proxy_pass http://sphinxrelay:3300/;
+  }
+  {{ end }}
+
 		{{ if (eq $serviceName "configurator") }}
 	location /configurator/ {
 		proxy_set_header Connection "";