Update README.md

Added build-essential to the list of required packages in debian/ubuntu

README.md

@@ -18,7 +18,7 @@ The KCM is only build, if the -DNO_SYSTEMD option is unset or set to false.
 * KF5: I18n, Auth, Config, Package, Declarative, CoreAddons, KCMUtils, Extra-Cmake-Modules, Kirigami2, Notifications
 
 ## Debian/Ubuntu command to install the build requirements:
-`sudo apt-get install libkf5config-dev libkf5auth-dev libkf5package-dev libkf5declarative-dev libkf5coreaddons-dev libkf5kcmutils-dev libkf5i18n-dev libqt5core5a libqt5widgets5 libqt5gui5 libqt5qml5 extra-cmake-modules qtbase5-dev kirigami2-dev libkf5kirigami2-5 libkf5notifications-dev qml-module-org-kde-kirigami2 cmake`
+`sudo apt-get install libkf5config-dev libkf5auth-dev libkf5package-dev libkf5declarative-dev libkf5coreaddons-dev libkf5kcmutils-dev libkf5i18n-dev libqt5core5a libqt5widgets5 libqt5gui5 libqt5qml5 extra-cmake-modules qtbase5-dev kirigami2-dev libkf5kirigami2-5 libkf5notifications-dev qml-module-org-kde-kirigami2 cmake`build-essential
 
 **Note:** This was tested on KDE Neon User Edition 5.13, which is based on Ubuntu 18.04 LTS (Debian 9 Stretch/Sid).