Update README to include mosquitto instructions for windows

README.md

@@ -25,6 +25,7 @@ In order to use this template and build a C++ application, you need to install a
 
   * **[cmake](https://cmake.org/download/)** (3.21 or newer)
   * **[git](https://git-scm.com/)** (to fetch dependencies)
+  * **[mosquitto](https://mosquitto.org/)** (required for MQTT integration)
   * **[slint](https://slint.dev/)** (optional)
   * C++ compiler that supports C++ 20
 
@@ -43,6 +44,15 @@ are:
 sudo apt install build-essential cmake git libxkbcommon-dev libxcb-xkb-dev libxkbcommon-x11-dev wayland-scanner++ wayland-protocols libwayland-dev libmosquittopp-dev
 ```
 
+### Windowd
+
+In case you want to build mecaps with its MQTT integration, you manually need to install mosquitto since we don't support building mosquitto from source (yet).
+
+You can find setup instructions and download links at
+
+<https://mosquitto.org/download/>
+
+
 ## Usage
 
 1. Clone or download this repository