DOCS-4186: Add port opening info etc (#4478)

Author: npentrel

docs/manage/fleet/system-settings.md

@@ -114,6 +114,16 @@ To configure your machine to disable TLS on the hosted HTTP server, you must spe
 }
 ```
 
+## Configure bind address and port
+
+To configure your machine to bind to a different port, set the `bind_address` in your machine settings:
+
+```json {class="line-numbers linkable-line-numbers"}
+"network": {
+  "bind_address": "localhost:8081"
+}
+```
+
 ## Configure operating system logging
 
 By default, the maximum disk space `journald` will use for `viam-server` logs is 512MB.

docs/operate/reference/architecture/machine-to-machine-comms.md

@@ -99,6 +99,7 @@ RDK Part 2 will be unaware of the actual plan and instead will only receive dist
 
 <li>RDK Part 1 returns an acknowledgement of the Motion Move request to the SDK application.</li>
 </ol>
+<br>
 
 ## Low-level inter-robot/SDK communication
 
@@ -116,3 +117,13 @@ In addition to gRPC, the RDK uses [WebRTC](https://webrtcforthecurious.com/) vid
 
 An outline of how WebRTC is used lives on [Go.dev](https://pkg.go.dev/go.viam.com/[email protected]/rpc#hdr-Connection), but in short, an RDK is always waiting on [app.viam.com](https://app.viam.com) to inform it of a connection requesting to be made to it whereby it sends details about itself and how to connect on a per connection basis.
 Once a connection is made, [app.viam.com](https://app.viam.com) is no longer involved in any packet transport and leaves it up to the two peers to communicate with each other.
+
+### Security implications
+
+Generally you do not need to open any ports or change your network configuration, if:
+
+- machines are on the internet and can successfully talk with `app.viam.com` and WebRTC works or
+- machines are on the same local network and mDNS and WebRTC are working
+
+If WebRTC is not available, you can communicate with `viam-server` over a gRPC connection.
+The default port is 8080 but you can configure another port in the [network settings](/manage/fleet/system-settings/#configure-bind-address-and-port).