[docs] tutorial/layers: clean up sample markdown
[docs] tutorial/layers: clean up sample markdown

gnina/gnina,wangg12/caffe,tackgeun/caffe,CZCV/s-dilation-caffe,gnina/gnina,gnina/gnina,gogartom/caffe-textmaps,tackgeun/caffe,CZCV/s-dilation-caffe,tackgeun/caffe,longjon/caffe,gogartom/caffe-textmaps,gogartom/caffe-textmaps,CZCV/s-dilation-caffe,CZCV/s-dilation-caffe,gnina/gnina,longjon/caffe,gogartom/caffe-textmaps,tackgeun/caffe,wangg12/caffe,gnina/gnina,gnina/gnina,longjon/caffe,wangg12/caffe,longjon/caffe,wangg12/caffe