Fix broken link on Github master branch readme.
Fix broken link on Github master branch readme.

msftberlin/azure-activedirectory-library-for-objc,AzureAD/azure-activedirectory-library-for-objc,msintuneappsdk/azure-activedirectory-library-for-objc,DocuSignDev/azure-activedirectory-library-for-ios,msintuneappsdk/azure-activedirectory-library-for-objc,msftberlin/azure-activedirectory-library-for-objc,AzureAD/azure-activedirectory-library-for-objc,AzureAD/azure-activedirectory-library-for-objc,DocuSignDev/azure-activedirectory-library-for-ios,AzureAD/azure-activedirectory-library-for-objc,AzureAD/azure-activedirectory-library-for-objc,smemane/azure-activedirectory-library-for-objc