docs: updated README with badges and minimal build instructions

Author: ErikBjare

README.md

@@ -1,6 +1,9 @@
 # aw-qt
 
-A service manager and tray icon managing aw-server and watchers created with Qt.
+[![GitHub Actions badge](https://github.com/ActivityWatch/aw-qt/workflows/Build/badge.svg)](https://github.com/ActivityWatch/aw-qt/actions)
+[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
+[![Typechecking: Mypy](http://www.mypy-lang.org/static/mypy_badge.svg)](http://mypy-lang.org/)
 
-[![Build Status](https://travis-ci.org/ActivityWatch/aw-qt.svg?branch=master)](https://travis-ci.org/ActivityWatch/aw-qt)
+A service manager and tray icon managing aw-server and watchers, built with Qt.
 
+For instructions how to build, see `Makefile`.