doc|packetizer: fixing typos
doc|packetizer: fixing typos

  * should be 'decoder' instead of 'encoder'
  * 'n' output bytes, not 'k'

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