update echo and ping example docs

docs/examples.echo.rst

@@ -1,17 +1,32 @@
 Echo Demo
 =========
 
-Copy the code below into a file called ``demo.py``.
-Install dependencies, preferably in a virtual environment, with:
+This example demonstrates a simple ``echo`` protocol.
 
-.. code-block:: bash
+.. code-block:: console
 
-    python -m pip install libp2p
+    $ python -m pip install libp2p
+    Collecting libp2p
+    ...
+    Successfully installed libp2p-x.x.x
+    $ echo-demo
+    Run this from the same folder in another console:
 
-Run the demo with ``python echo.py`` and copy the output.
+    echo-demo -p 8001 -d /ip4/127.0.0.1/tcp/8000/p2p/16Uiu2HAmAsbxRR1HiGJRNVPQLNMeNsBCsXT3rDjoYBQzgzNpM5mJ
 
-Open a second terminal, navigate to the folder that contains ``echo.py``, then paste
-and run the copied line.
+    Waiting for incoming connection...
+
+Copy the line that starts with ``echo-demo -p 8001``, open a new terminal in the same
+folder and paste it in:
+
+.. code-block:: console
+
+    $ echo-demo -p 8001 -d /ip4/127.0.0.1/tcp/8000/p2p/16Uiu2HAmAsbxRR1HiGJRNVPQLNMeNsBCsXT3rDjoYBQzgzNpM5mJ
+
+    I am 16Uiu2HAmE3N7KauPTmHddYPsbMcBp2C6XAmprELX3YcFEN9iXiBu
+    Sent: hi, there!
+
+    Got: hi, there!
 
 .. literalinclude:: ../examples/echo/echo.py
     :language: python

docs/examples.ping.rst

@@ -1,17 +1,31 @@
 Ping Demo
 =========
 
-Copy the code below into a file called ``ping.py``.
-Install dependencies, preferably in a virtual environment, with:
+This example demonstrates how to use the libp2p ``ping`` protocol.
 
-.. code-block:: bash
+.. code-block:: console
 
-    python -m pip install libp2p
+    $ python -m pip install libp2p
+    Collecting libp2p
+    ...
+    Successfully installed libp2p-x.x.x
+    $ ping-demo
+    Run this from the same folder in another console:
 
-Run the demo with ``python ping.py`` and copy the output.
+    ping-demo -p 8001 -d /ip4/127.0.0.1/tcp/8000/p2p/QmXfptdHU6hqG95JswxYVUH4bphcK8y18mhFcgUQFe6fCN
 
-Open a second terminal, navigate to the folder that contains ``ping.py``, then paste
-and run the copied line.
+    Waiting for incoming connection...
+
+Copy the line that starts with ``ping-demo -p 8001``, open a new terminal in the same
+folder and paste it in:
+
+.. code-block:: console
+
+    $ ping-demo -p 8001 -d /ip4/127.0.0.1/tcp/8000/p2p/QmXfptdHU6hqG95JswxYVUH4bphcK8y18mhFcgUQFe6fCN
+    sending ping to QmXfptdHU6hqG95JswxYVUH4bphcK8y18mhFcgUQFe6fCN
+    received pong from QmXfptdHU6hqG95JswxYVUH4bphcK8y18mhFcgUQFe6fCN
+
+The full source code for this example is below:
 
 .. literalinclude:: ../examples/echo/echo.py
     :language: python