sandbox: clarifying mixed-radix fft test objective in 'help'
sandbox: clarifying mixed-radix fft test objective in 'help'

jgaeddert/liquid-dsp,JayKickliter/liquid-dsp,andrepuschmann/liquid-dsp,wangning223/liquid-dsp,JayKickliter/liquid-dsp,andrepuschmann/liquid-dsp,jgaeddert/liquid-dsp,jgaeddert/liquid-dsp,andrepuschmann/liquid-dsp,manuts/liquid-dsp,JayKickliter/liquid-dsp,biotrump/liquid-dsp,jgaeddert/liquid-dsp,cjcliffe/liquid-dsp,andrepuschmann/liquid-dsp,cjcliffe/liquid-dsp,wangning223/liquid-dsp,manuts/liquid-dsp,biotrump/liquid-dsp,manuts/liquid-dsp,andrepuschmann/liquid-dsp,cjcliffe/liquid-dsp,JayKickliter/liquid-dsp,wangning223/liquid-dsp,manuts/liquid-dsp,biotrump/liquid-dsp,wangning223/liquid-dsp,manuts/liquid-dsp,jgaeddert/liquid-dsp,wangning223/liquid-dsp,biotrump/liquid-dsp,biotrump/liquid-dsp,cjcliffe/liquid-dsp,JayKickliter/liquid-dsp,cjcliffe/liquid-dsp