Link to new BGP documentation from 'how-to-run'

docs/how-to-run.adoc

@@ -266,7 +266,8 @@ last = "192.168.1.29"
 
 This is a range of IP addresses on your external network that Omicron can assign to externally-facing services (like DNS and the API).  You'll need to change these if you've picked different addresses for your external network.  See <<_external_networking>> above for more on this.
 
-You will also need to update route information if your `$GATEWAY_IP` differs from the default:
+You will also need to update route information if your `$GATEWAY_IP` differs from the default.
+The below example demonstrates a single static gateway route; in-depth explanations for testing with BGP can be found https://docs.oxide.computer/guides/system/network-preparations#_rack_switch_configuration_with_bgp[in the Network Preparations guide] and https://docs.oxide.computer/guides/operator/configuring-bgp[the Configuring BGP guide]:
 
 [source,toml]
 ----
@@ -287,8 +288,7 @@ infra_ip_last = "192.168.1.30"
 # This array can typically be safely left empty for home/local use,
 # otherwise this is a list of { asn: u32, originate: ["<v4 network>"] }
 # structs which will be be inserted when Nexus is started by sled-agent.
-# These prefixes will be advertised to peers set below.
-# see: common/src/api/internal/shared.rs – BgpConfig
+# See the 'Network Preparations' guide linked above.
 bgp = []
 
 [[rack_network_config.ports]]