docs(health-sdk): Add readme file and describe example app's flavors …

…in its readme

IPC-111

health-sdk/example-app/README.md

@@ -0,0 +1,44 @@
+Gini Health SDK Example App
+=========================
+
+This example app provides you with a sample usage of the Gini Health SDK.
+
+The Gini Health API Library is used for analyzing documents and creating payment requests.
+
+Before using the Gini Health SDK example app, you need to set your Gini Health API client id and secret by creating a
+`local.properties` file in this folder containing a `clientId` and a `clientSecret` property.
+
+ProGuard 
+========
+
+A sample ProGuard configuration file is included in the example app's directory called `proguard-rules.pro`. 
+
+The release build is configured to run ProGuard. You need a keystore with a key to sign it. Create a keystore with a key and provide them in
+the `gradle.properties` or as arguments for the build command:
+
+``` 
+$ ./gradlew health-sdk:example-app:assembleRelease \ 
+    -PreleaseKeystoreFile=<path to keystore> \ 
+    -PreleaseKeystorePassword=<keystore password> \ 
+    -PreleaseKeyAlias=<key alias> \ 
+    -PreleaseKeyPassword=<key password> \
+    -PclientId=<Gini API client id> \
+    -PclientSecret=<Gini API client secret>
+``` 
+
+Flavors
+=======
+
+The example app has three flavors: `dev`, `prod` and `qa`. The `dev` flavor is used by default. The `prod` flavor
+is used for creating release builds which can be shared with clients while the `qa` flavor is used for creating release builds
+for QA purposes. The difference between `prod` and `qa` is that `qa` allows using custom SSL root certificates for
+SSL proxies (e.g. Charles Proxy).
+
+Payment Providers for testing the Health SDK
+============================================
+
+Payment Providers for testing are provided by the Gini Bank SDK's example app. Run `bundle exec fastlane install_test_payment_provider_apps` in the repository root to install test payment provider apps 
+on all running emulators and connected devices. You can run `bundle exec fastlane uninstall_test_payment_provider_apps`
+to uninstall the test payment provider apps.
+
+Please view the Gini Bank SDK example app's readme at `bank-sdk/example-app/README.md` for more details.