updated readme

README.md

 * Clicking on a window makes slrn return the dimensions of the window.
 * Clicking and dragging causes a selection rectangle to appear, renders pretty well (compared to scrot). And will return the dimensions of that rectangle in absolute screen coords.
 * On startup it turns your cursor into a crosshair, then adjusts the cursor into angles as you drag the selection rectangle.
-* Supports simple arguments (change selection rectangle border size, x display, padding, etc. )
+* Supports simple arguments (change selection rectangle border size, x display, padding, click tolerance, etc. )
+
+practical applications
+----------------------
+slrn can be used to create a video recording script in only two lines of code.
+```bash
+#!/bin/bash
+eval `slrn`
+ffmpeg -f x11grab -s "$Wx$H" -i :0.0+$X,$Y -f alsa -i pulse ~/myfile.webm
+```
+slrn lets you select a region or window and ffmpeg will record it in the format of your choice!
+Combined with keybinds and a server on your filesystem you can make a really neat and unobtrusive screenshooter.