Add travis build badge

ltjax · ltjax · commit 9af7e3aa9280 · 2020-04-16T18:15:53.000+02:00
diff --git a/README.md b/README.md
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 # Steam Controller Library
 
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 This is a small C++ library for Windows, Linux and Mac OS systems that allows accessing the Steam Controller without steam. It exposes all button and axis data as well as acceleration, angular velocity and spatial orientation. 
 
