all: writing correct routers setup to config file

When running on routers, ctrld leverages default setup, let dnsmasq runs
on port 53, and forward queries to ctrld listener on port 5354. However,
this setup is not serialized to config file, causing confusion to users.

Fixing this by writing the correct routers setup to config file. While
at it, updating documentation to refelct that, and also adding note that
changing default router setup could break things.

README.md

@@ -73,7 +73,13 @@ $ go install github.com/Control-D-Inc/ctrld/cmd/ctrld@latest
 $ docker build -t controld/ctrld .
 $ docker run -d --name=ctrld -p 53:53/tcp -p 53:53/udp controld/ctrld --cd=p2 -vv
 ```
+-----
+*NOTE*
 
+When running inside container, and listener address is set to "127.0.0.1:53", `ctrld` will change
+the listen address to "0.0.0.0:53", so users can expose the port to outside.
+
+----
 
 # Usage
 The cli is self documenting, so free free to run `--help` on any sub-command to get specific usages. 
@@ -176,6 +182,15 @@ In order to start `ctrld` as a DNS provider, simply run `./ctrld setup auto` com
 
 In this mode, and when Control D upstreams are used, the router will [relay your network topology](https://docs.controld.com/docs/device-clients) to Control D (LAN IPs, MAC addresses, and hostnames), and you will be able to see your LAN devices in the web panel, view analytics and apply unique profiles to them. 
 
+----
+*NOTE*
+
+`ctrld` will try leveraging default setup on routers, so changing routers default configuration would causes things won't work as expected (For example, changing dnsmasq configuration).
+
+Advanced users who want to play around, just run `ctrld` in [Service Mode](#service-mode) with custom configuration.
+
+----
+
 ### Control D Auto Configuration
 Application can be started with a specific resolver config, instead of the default one. Simply supply your Resolver ID with a `--cd` flag, when using the `run` (foreground) or `start` (service) or `setup` (router) modes.