Document the net_mapper

README.md

@@ -15,6 +15,31 @@ Do not send messages immediately to the dataspace passed `json_socket_translator
 A utility that sends a message to `$SYNDICATE_SOCK` in the form `<ARGV0 ARG1 … ARGVn>`.
 The `$SYNDICATE_STEP` variables sets the SturdyRef capability with a default to the SturdyRef generated by `<ref { oid: "syndicate" key: #x"" }>`.
 
+
+## net_mapper
+
+Publishes ICMP packet round-trip-times. See [net_mapper.prs](./net_mapper.prs) for a protocol description. [Source](./src/net_mapper.nim).
+
+Example script:
+```
+? <machine-dataspace ?machine> [
+  $machine ? <rtt "10.0.33.136" ?min ?avg ?max> [
+    $log ! <log "-" { ping: { min: $min avg: $avg max: $max } }>
+  ]
+
+  $config [
+    <require-service <daemon net_mapper>>
+    <daemon net_mapper {
+      argv: ["/bin/net_mapper"]
+      protocol: application/syndicate
+    }>
+    ? <service-object <daemon net_mapper> ?cap> [
+      $cap { dataspace: $machine }
+    ]
+  ]
+]
+```
+
 ## preserve_process_environment
 
 This utility serializes it's process environment to Preserves and prints it to stdout.