fixed md syntax error

README.md

 # Collection of Bash code snippets, mostly one liners, to ease file handling among other things
 Collection of notes
 #### rename files to reverse order
-```N=1; ls -tr -1 *.jpg | tac | while read file; do mv "$file" "$N".jpg; N=$((N+1)); done```
+
+`N=1; ls -tr -1 *.jpg | tac | while read file; do mv "$file" "$N".jpg; N=$((N+1)); done`  
 
 #### rotate all images using imagemagick
 
 `mogrify` overwrites existing images which is what makes it different from `convert`
 
 #### cut poly-shape out of image, crop image to its boundaries, fill surrounding holes in certain color or transparent (for all jpgs in folder)
+
 `for f in ./*.jpg; do convert "$f" \( -clone 0 -fill black -colorize 100 -fill white -draw "polygon 3276,2421 4945,2407 4956,4708 3287,4722" \) -alpha off -compose copy_opacity -composite -trim +repage 41050648/"$f"_left.jpg; done`  
 
 #### do something inside each folder of this folder
+
 ```
 for d in */; do
   cd $d;