add readme for vnc image (#63)

* add readme for vnc image

* add -N flag

* Update README.md

Co-authored-by: Katie Horne <katie@coder.com>

images/vnc/README.md

@@ -0,0 +1,16 @@
+# VNC in Coder
+
+A [sample image](https://github.com/cdr/enterprise-images/tree/main/images/vnc) for Coder that uses [noVNC](https://github.com/novnc/noVNC) as the client and [TigerVNC](https://tigervnc.org) as the server.
+
+## To connect
+
+- Option 1 (Web): Create a dev URL on port `6081` and navigate to it
+- Option 2 (SSH Tunneling): Use SSH tunneling to expose the VNC server to your local machine. You will need the [coder-cli](https://github.com/cdr/coder-cli) and a VNC client installed on your local machine.
+
+    ```sh
+    coder config-ssh
+    # Forward the remote VNC server to your local machine
+    ssh -L -N 5990:localhost:localhost:5990 coder.[env-name]
+    # You will not see any output if it succeeds, but you
+    # will be able to connect your VNC client to localhost:5990
+    ```