Added Miniflux custom service

Co-authored-by: Moritz Kreutzer
Co-authored-by: Reiko Kaps 
Co-authored-by: igorkulman

docs/customservices.md

@@ -32,6 +32,7 @@ Available services are located in `src/components/`:
 - [Matrix](#matrix)
 - [Mealie](#mealie)
 - [Medusa](#medusa)
+- [Miniflux](#miniflux)
 - [Nextcloud](#nextcloud)
 - [OctoPrint / Moonraker](#octoprintmoonraker)
 - [Olivetin](#olivetin)
@@ -389,6 +390,22 @@ The url must be the root url of Medusa application.
 
 **API Key**: The Medusa API key can be found in General configuration > Interface. It is needed to access Medusa API.
 
+## Miniflux
+
+Displays the number of unread articles from your Miniflux RSS reader.
+
+```yaml
+- name: "Miniflux"
+  type: "Miniflux"
+  logo: "assets/tools/sample.png"
+  url: https://my-service.url
+  apikey: "<---insert-api-key-here--->"
+  style: "status" # Either "status" or "counter"
+  checkInterval: 60000 # Optional: Interval (in ms) for updating the unread count
+```
+
+**API Key**: Generate an API key in Miniflux web interface under **Settings > API Keys > Create a new API key**
+
 ## Nextcloud
 
 Displays Nextcloud version and shows if Nextcloud is online, offline, or in [maintenance