instructions how to build and flash with platformio

.gitignore

@@ -2,3 +2,8 @@
 .piolibdeps
 .clang_complete
 .gcc-flags.json
+bin/
+include/
+lib/
+local/
+share/

README.md

@@ -11,7 +11,15 @@ Soundboard (computer program), a web application or computer program with button
 tbd
 
 ## Build
-tbd
+```bash
+git clone https://dev.xd0.de/hendrik/soundboard.git
+cd soundboard
+virtualenv .
+source bin/activate
+pip install -U platformio
+platformio run
+platformio run -t upload
+```
 
 ## ToDo
 * Prototype