update readme

README.md

@@ -8,6 +8,8 @@ IP Tunneling over MQTT
 
 Designed to allow remote access for IoT/Edge devices connected to an existing MQTT network.
 
+### Working Mechanism
+
 IP packets are sent as MQTT payloads on 2 topics:
 - Client -> Server: `<topic>` (payload prepended by tunnel ID)
 - Server -> Client: `<topic>/<base64-tunnel-id>`
@@ -20,10 +22,18 @@ The MQTT connection is assumed to be secure & have authentication mechanisms in
 Zika offers no extra layers of security on top of the MQTT connection,
 it's possible capture/inject arbitrary IP packets to/from the target device if the MQTT connection/broker is compromised.
 
-### Configuration
+### Config & Run
 
 See [zika_config.example.toml](zika_config.example.toml)
 
+Copy `zika-client` and `zika_config.toml` to the same directory
+
+Run `zika-client`
+
+- Linux: `setcap cap_net_admin+eip zika-client`
+- macOS: requires `sudo`
+- Windows: run as Administrator, requires `wintun.dll` in same directory
+
 ### Building
 
 ```