Added CI

.github/workflows/android-build.yml

@@ -0,0 +1,40 @@
+name: Build
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up JDK
+        uses: actions/setup-java@v2
+        with:
+          java-version: '11'
+          distribution: 'temurin'
+          cache: gradle
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
+      - name: Build with Gradle
+        run: ./gradlew build
+
+      - name: Upload our APK
+        uses: actions/upload-artifact@v2.2.0
+        with:
+          name: APK
+          path: app/build/outputs/apk/release/app-release-unsigned.apk
+
+      - name: Upload lint report
+        uses: actions/upload-artifact@v2.2.0
+        with:
+          name: Lint report
+          path: app/build/reports/lint-results-debug.html

README.md

@@ -1,4 +1,9 @@
 # OpenBoard
+
+[![Build](https://github.com/openboard-team/openboard/actions/workflows/android-build.yml/badge.svg)](https://github.com/openboard-team/openboard/actions/workflows/android-build.yml)
+![GitHub release (latest by date)](https://img.shields.io/github/v/release/openboard-team/openboard)
+![GitHub commits since latest release (by date)](https://img.shields.io/github/commits-since/openboard-team/openboard/latest)
+
 <a href='https://f-droid.org/packages/org.dslul.openboard.inputmethod.latin'><img src='https://fdroid.gitlab.io/artwork/badge/get-it-on.png' alt='Get it on F-Droid' height='80'></a>
 <a href='https://play.google.com/store/apps/details?id=org.dslul.openboard.inputmethod.latin&pcampaignid=pcampaignidMKT-Other-global-all-co-prtnr-py-PartBadge-Mar2515-1'><img alt='Get it on Google Play' src='https://play.google.com/intl/en_us/badges/static/images/badges/en_badge_web_generic.png' height='80px'/></a>