Apple has also just released watchOS 2.1. This is the first major update to watchOS 2. In this version we see mainly bug fixes and improvements. It adds support for multiple languages and also has fixes for issues with Calendar, Power Reserve mode, and third-party apps.
To get this update, go to the Watch app > General > Software update > watchOS 2.1. You must be in ranage of your iPhone, charged to at least 50%, and connected to your charger in install the update.