Added custom service jellystat (#770)

Added custom service jellystat

docs/customservices.md

@@ -36,6 +36,7 @@ within Homer:
   - [PiAlert](#pialert)
   - [Immich](#immich)
   - [OpenHAB](#openhab)
+  - [Jellystat](#jellystat)
   - [Home Assistant](#home-assistant)
 
 If you experiencing any issue, please have a look to the [troubleshooting](troubleshooting.md) page.
@@ -465,6 +466,22 @@ You need to set the type to OpenHAB, provide an api key and enable cors on OpenH
 To create an API token on OpenHAB, follow the [official documentation here](https://www.openhab.org/docs/configuration/apitokens.html).  
 To enable cors on OpenHAB, edit your services/runtime.cfg and uncomment or add this line: `org.openhab.cors:enable=true`
 
+## Jellystat
+
+The Jellystat serice display the number of concurrent streams on your jellyfin server.
+The Jellystat server must be running behind a reverse proxy to add some cors headers:
+ - Access-Control-Allow-Origin: ${your_domain}
+ - Access-Control-Allow-Headers: Authorization
+
+```yaml
+- name: "Jellystat"
+  logo: "assets/tools/jellystat.png"
+  url: "http://192.168.1.154:3000"
+  type: "Jellystat"
+  apikey: "<---insert-api-key-here--->"
+```
+You can create an API key in the dashboard of you jellystat server: settings/API Keys -> Add Key
+
 ## Home Assistant
 
 You need to set the type to HomeAssistant, provide an api key and enable cors on Home Assistant.
@@ -479,4 +496,4 @@ You need to set the type to HomeAssistant, provide an api key and enable cors on
   separator: " " # optional, how to separate items
 ```
 To create an API token on HomeAssistant, follow the [official documentation here](https://developers.home-assistant.io/docs/auth_api/#long-lived-access-token).  
-To enable cors on HomeAssistant, edit your `configuration.yml` and add the IP of Homer to `https: cors_allowed_origins`
+To enable cors on HomeAssistant, edit your `configuration.yml` and add the IP of Homer to `https: cors_allowed_origins`