Added section about how to acquire an access token outside of a React component.
Added section about how to acquire an access token outside of a React component.

AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js,AzureAD/microsoft-authentication-library-for-js