Small update of the Matrix documentation

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/Matrix.kt

@@ -43,7 +43,8 @@ import javax.inject.Inject
 
 /**
  * This is the main entry point to the matrix sdk.
- * To get the singleton instance, use getInstance static method.
+ * <br/>
+ * See [Companion.createInstance] to create an instance. The app should create and manage the instance itself.
  */
 class Matrix private constructor(context: Context, matrixConfiguration: MatrixConfiguration) {
 
@@ -74,9 +75,7 @@ class Matrix private constructor(context: Context, matrixConfiguration: MatrixCo
 
     fun getUserAgent() = userAgentHolder.userAgent
 
-    fun authenticationService(): AuthenticationService {
-        return authenticationService
-    }
+    fun authenticationService() = authenticationService
 
     fun rawService() = rawService
 
@@ -84,9 +83,7 @@ class Matrix private constructor(context: Context, matrixConfiguration: MatrixCo
 
     fun homeServerHistoryService() = homeServerHistoryService
 
-    fun legacySessionImporter(): LegacySessionImporter {
-        return legacySessionImporter
-    }
+    fun legacySessionImporter() = legacySessionImporter
 
     fun workerFactory(): WorkerFactory = matrixWorkerFactory
 
@@ -143,6 +140,9 @@ class Matrix private constructor(context: Context, matrixConfiguration: MatrixCo
             return instance
         }
 
+        /**
+         * @return a String with details about the Matrix SDK version
+         */
         fun getSdkVersion(): String {
             return BuildConfig.SDK_VERSION + " (" + BuildConfig.GIT_SDK_REVISION + ")"
         }