add github actions workflow

Author: marcelkottmann

.github/workflows/ci.yml

@@ -0,0 +1,11 @@
+name: Build
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1
+      - name: Build
+        run: docker run -v ${PWD}:/opt/esp32-javascript -w /opt/esp32-javascript -t espressif/idf idf.py build

README.md

@@ -1,5 +1,7 @@
 # esp32-javascript
 
+![](https://github.com/marcelkottmann/esp32-javascript/workflows/Build/badge.svg)
+
 "Lightweight" JS interpreter for ESP32. Provides JS-based eventloop implementation
 and native asynchronous network and timer functions.
 Because of the limited memory on ESP32-WROOM modules, the full functionality is currently only realizable on ESP32-WROVER modules, that include additional 4MB of SPIRAM memory.