Add sample doc for elgato light service

Adds sample documentation for elgato light service (codeoverflow-org/nodecg-io#247).

Author: hlxid

docs/samples/elgato-light.md

@@ -0,0 +1,50 @@
+## Using the elgato-light sample bundle
+
+The elgato-light example bundle in `samples/elgato-light` demonstrates the ability to controll elgato keylights and elgato lightstrips. Here is a guide to how to get it working.
+
+### Prerequisites
+
+-   Working NodeCG & nodecg-io installation
+-   at least one elgato keylight or lightstrip
+
+### Configure the elgato-light sample bundle
+
+1. Start nodecg with nodecg-io installed. The elgato-light sample bundle is currently part of it so it should also be loaded.
+
+2. Go to the `nodecg-io` tab in the nodecg dashboard.
+
+3. Login using your password. If this is your first run, then enter the password with which you want to encrypt your configurations and credentials.
+
+4. Create a new elgato-light service instance using the left upper menu.
+
+5. Enter configuration:
+
+    The created instance should be automatically selected, if not select it in the upper left menu. Enter the IP address to your light and the type (`KeyLight` or `LightStrip`) in monaco (the text-editor on the right) in this format:
+
+    ```json
+    {
+        "lights": [
+            {
+                "ipAddress": "xxx.xxx.xxx.xxx",
+                "lightType": "KeyLight",
+                "name": "MyLight1"
+            }
+        ]
+    }
+    ```
+
+    You can add as many lights to this service as you wish by adding more objects inside the `lights` array.
+
+    `name` is optional and can be used to identify lights in bundles. You can omit it if you don't use the name to get it in any bundle.
+
+    After entering it, click save.
+
+    _Note:_ If you don't see monaco on the right, try reloading the page.
+
+6. Set the created elgato-light service instance to the service dependency of the elgato-light sample bundle.
+
+    Select the elgato-light example bundle and the elgato-light service in the left bottom menu and then select the service instance that should be used by the elgato-light example bundle (in this case the name of the previously created elagto-light instance).
+
+7. Check the nodecg logs
+
+    Your lights should blink for three seconds and you should see the current brightness in the nodecg logs.

mkdocs.yml

@@ -54,6 +54,7 @@ nav:
           - Android: samples/android.md
           - Debug: samples/debug.md
           - Discord sample: samples/discord.md
+          - Elgato Light sample: samples/elgato-light.md
           - IntelliJ sample: samples/intellij.md
           - IRC: samples/irc.md
           - Midi: