docs: Added build instructions

README.md

@@ -10,11 +10,25 @@ Android application for reading storybooks.
 
 Note: This app depends on the [elimu.ai Content Provider](https://github.com/elimu-ai/content-provider) to be installed.
 
+## Development 👩🏽‍💻
+
+Compile APK:
+
+```
+./gradlew clean build
+```
+
+Install APK:
+
+```
+adb install app/build/outputs/apk/debug/ai.elimu.vitabu-<versionCode>-debug.apk
+```
+
 ---
 
 ## About the elimu.ai Community
 
 ![elimu ai-tagline](https://user-images.githubusercontent.com/15718174/54360503-e8e88980-465c-11e9-9792-32b513105cf3.png)
 
- * For a high-level description of the project, see https://github.com/elimu-ai/wiki/blob/master/README.md.
+ * For a high-level description of the project, see https://github.com/elimu-ai/wiki#readme.
  * For project milestones, see https://github.com/elimu-ai/wiki/projects.