License file is missing

[icecoffin]

The license file is present in the main repository (https://github.com/AppsFlyerSDK/AppsFlyerFramework/blob/master/LICENSE) but is missing from this one (AppsFlyerFramework-Static and AppsFlyerFramework-Strict have the same issue). We use a tool to generate the list of acknowledgments in our app based on the license files. Since the license file is missing here, the AppsFlyer SDK is excluded from the acknowledgments list.