Added tutorial on how to send/receive message with 2 mycelium peers running the same host

docs/docs/rhai/mycelium_tutorial.md

@@ -329,4 +329,60 @@ try {
 } catch(err) {
     print(`Error sending message: ${err}`);
 }
-```
+```
+
+### Example: setting up 2 different Mycelium peers on same the host and sending/receiving a message
+
+#### Obtain Mycelium
+
+- Download the latest Mycelium binary from https://github.com/threefoldtech/mycelium/releases/
+- Or compile from source
+
+#### Setup
+> `cd myceliumd && cargo build`
+
+- Create two different private key files. Each key file should contain exactely 32 bytes. In this example we'll save these files as `sender.bin` and `receiver.bin`. Note: generate your own 32-byte key files, the values below are just used as examples.
+> `echo '9f3d72c1a84be6f027bba94cde015ee839cedb2ac4f2822bfc94449e3e2a1c6a' > sender.bin`
+
+> `echo 'e81c5a76f42bd9a3c73fe0bb2196acdfb6348e99d0b01763a2e57ce3a4e8f5dd' > receiver.bin`
+
+#### Start the nodes
+- **Sender**: this node will have the API server hosted on `127.0.0.1:1111` and the JSON-RPC server on `127.0.0.1:8991`.
+> `sudo ./mycelium --key-file sender.bin --disable-peer-discovery --disable-quic --no-tun --api-addr 127.0.0.1:1111 --jsonrpc-addr 127.0.0.1:8991`
+
+- **Receiver**: this node will have the API server hosted on `127.0.0.1:2222` and the JSON-RPC server on `127.0.0.1:8992`.
+> `sudo ./mycelium --key-file receiver.bin --disable-peer-discovery --disable-quic --no-tun --api-addr 127.0.0.1:2222 --jsonrpc-addr 127.0.0.1:8992 --peers tcp://<UNDERLAY_IP_SENDER>:9651`
+- Obtain the Mycelium overlay IP by running `./mycelium --key-file receiver.bin --api-addr 127.0.0.1:2222 inspect`. **Replace this IP as destination  in the [mycelium_receive_message.rhai](../../../examples/mycelium/mycelium_receive_message.rhai) example**.
+
+#### Execute the examples
+- First build by executing `./build_herdo.sh` from the SAL root directory
+- `cd target/debug`
+
+- Run the sender script: `sudo ./herodo --path ../../examples/mycelium/mycelium_send_message.rhai`
+```
+Executing: ../../examples/mycelium/mycelium_send_message.rhai
+
+Sending a message:
+Attempting to send message to 50e:6d75:4568:366e:f75:2ac3:bbb1:3fdd on topic 'test_topic'
+result: #{"id": "bfd47dc689a7b826"}
+Message sent: 
+Message ID: bfd47dc689a7b826
+Script executed successfull
+```
+
+- Run the receiver script: `sudo ./herodo --path ../../examples/mycelium/mycelium_receive_message.rhai`
+```
+Executing: ../../examples/mycelium/mycelium_receive_message.rhai
+
+Receiving messages:
+Listening for messages on topic 'test_topic'...
+Received a message:
+  Message id: bfd47dc689a7b826
+  Message from: 45d:26e1:a413:9d08:80ce:71c6:a931:4315
+  Topic: dGVzdF90b3BpYw==
+  Payload: SGVsbG8gZnJvbSBSaGFpIHNlbmRlciE=
+Finished attempting to receive messages.
+Script executed successfully
+```
+> Decoding the payload `SGVsbG8gZnJvbSBSaGFpIHNlbmRlciE=` results in the expected `Hello from Rhai sender!` message. Mission succesful!
+