docs: Match and pass /litrpc.* locations in nginx

Also escape the "." for more precise regex matching

Author: Carl Dong

doc/example-nginx.conf

@@ -39,17 +39,7 @@ http {
             proxy_pass https://172.17.0.1:8443/;
         }
 
-        location ~* ^/lnrpc.Lightning/ {
-            # This cannot have a slash at the end!
-            proxy_pass https://$lnd_backend;
-        }
-
-        location ~* ^/looprpc.SwapClient/ {
-            # This cannot have a slash at the end!
-            proxy_pass https://$lnd_backend;
-        }
-
-        location ~* ^/poolrpc.Trader/ {
+        location ~* ^/(ln|loop|pool|lit)rpc\. {
             # This cannot have a slash at the end!
             proxy_pass https://$lnd_backend;
         }