Update Readme to remove stray bash in commands (#248)

exercises/basic_tunnel/README.md

@@ -86,30 +86,50 @@ to hosts. For this step you will need to add your forwarding rules to the
 
 ## Step 2: Run your solution
 
-1. In your shell, run: ```bash make run ``` This will:
+1. In your shell, run:
+   ```bash
+   make run
+   ``` 
+   This will:
    * compile `basic_tunnel.p4`, and
    * start a Mininet instance with three switches (`s1`, `s2`, `s3`) configured
      in a triangle, each connected to one host (`h1`, `h2`, and `h3`).
    * The hosts are assigned IPs of `10.0.1.1`, `10.0.2.2`, and `10.0.3.3`.
 
 2. You should now see a Mininet command prompt. Open two terminals for `h1` and
-`h2`, respectively: ```bash mininet> xterm h1 h2 ```
+`h2`, respectively: 
+  ```bash
+  mininet> xterm h1 h2
+  ```
 3. Each host includes a small Python-based messaging client and server. In
-`h2`'s xterm, start the server: ```bash ./receive.py ```
+`h2`'s xterm, start the server: 
+  ```bash 
+  ./receive.py
+  ```
 4. First we will test without tunneling. In `h1`'s xterm, send a message to
-`h2`: ```bash ./send.py 10.0.2.2 "P4 is cool" ``` The packet should be received
+`h2`: 
-at `h2`. If you examine the received packet you should see that is consists of
+  ```bash
-an Ethernet header, an IP header, a TCP header, and the message. If you change
+  ./send.py 10.0.2.2 "P4 is cool"
-the destination IP address (e.g. try to send to `10.0.3.3`) then the message
+  ```
-should not be received by h2, and will instead be received by h3.
+  The packet should be received at `h2`. If you examine the received packet 
-5. Now we test with tunneling. In `h1`'s xterm, send a message to `h2`: ```bash
+  you should see that is consists of an Ethernet header, an IP header, a TCP
-./send.py 10.0.2.2 "P4 is cool" --dst_id 2``` The packet should be received at
+  header, and the message. If you change the destination IP address (e.g. try
-`h2`. If you examine the received packet you should see that is consists of an
+  to send to `10.0.3.3`) then the message should not be received by `h2`, and
-Ethernet header, a tunnel header, an IP header, a TCP header, and the message. 
+  will instead be received by `h3`.
-6. In `h1`'s xterm, send a message: ```bash ./send.py 10.0.3.3 "P4 is cool"
+5. Now we test with tunneling. In `h1`'s xterm, send a message to `h2`: 
---dst_id 2``` The packet should be received at `h2`, even though that ip
+  ```bash
-address is the address of `h3`. This is because the switch is no longer using
+  ./send.py 10.0.2.2 "P4 is cool" --dst_id 2
-the IP header for routing when the `MyTunnel` header is in the packet. 
+  ```
+  The packet should be received at `h2`. If you examine the received packet you
+  should see that is consists of an Ethernet header, a tunnel header, an IP header,
+  a TCP header, and the message. 
+6. In `h1`'s xterm, send a message: 
+  ```bash
+  ./send.py 10.0.3.3 "P4 is cool" --dst_id 2
+  ```
+  The packet should be received at `h2`, even though that IP address is the address
+  of `h3`. This is because the switch is no longer using the IP header for routing
+  when the `MyTunnel` header is in the packet. 
 7. Type `exit` or `Ctrl-D` to leave each xterm and the Mininet command line.
 
 
@@ -158,7 +178,9 @@ logic errors in your implementation.
 In the latter two cases above, `make` may leave a Mininet instance running in
 the background. Use the following command to clean up these instances:
 
-```bash make stop ```
+```bash
+make stop
+```
 
 ## Next Steps