Update the doc

matrix-sdk-android/docs/modules.md

@@ -1,3 +1,18 @@
 # Module matrix-sdk-android
 
-Doc for the module!
+## Welcome to the matrix-sdk-android documentation!
+
+This pages list the complete API that this SDK is exposing to a client application.
+
+*We are still building the documentation, so everything is not documented yet.*
+
+A few entry points:
+
+- **Matrix**: The app will have to create and manage a Matrix object.
+- From this **Matrix** object, you will be able to get various services, including the **AuthenticationService**.
+- With this **AuthenticationService** you will be able to get an existing **Session**, or create one using a **LoginWizard** or a **RegistrationWizard**, which will finally give you a **Session**.
+- From the **Session**, you will be able to retrieve many Services, including the **RoomService**.
+- From the **RoomService**, you will be able to list the rooms, create a **Room**, and get a specific **Room**.
+- And from a **Room**, you will be able to do many things, including get a **Timeline**, send messages, etc.
+
+Please read the whole documentation to learn more!

matrix-sdk-android/docs/packages.md

@@ -1,3 +1,3 @@
 # Package org.matrix.android.sdk.api
 
-Doc for the package!
+This is the root package of the API exposed by this SDK.