Add development instructions (PostHog#12)

Co-authored-by: Alex Gyujin Kim <[email protected]>

README.md

@@ -4,6 +4,14 @@ Please see the main [PostHog docs](https://posthog.com/docs).
 
 Specifically, the [Android integration](https://posthog.com/docs/integrations/android-integration) details.
 
+## Development guide
+
+1. Install Android Studio
+2. Follow instructions here for setup https://developer.android.com/studio/run/emulator
+3. Make sure you have Java 8 installed locally - `brew tap adoptopenjdk/openjdk && brew install --cask adoptopenjdk8`
+4. Change the JDK in IntelliJ to build using the correct version.
+5. Select `posthog-sample` and the device on the top bar and click run
+
 ## Questions?
 
 ### [Join our Slack community.](https://join.slack.com/t/posthogusers/shared_invite/enQtOTY0MzU5NjAwMDY3LTc2MWQ0OTZlNjhkODk3ZDI3NDVjMDE1YjgxY2I4ZjI4MzJhZmVmNjJkN2NmMGJmMzc2N2U3Yjc3ZjI5NGFlZDQ)