Update README.md

Author: monkstone

README.md

@@ -4,7 +4,7 @@ A port of [Filters4Processing][] to ruby-processing
 A growing collection of pixel shaders ported to Processing to be used with the `filter()` function. Most of these shaders come from the excellent [Shadertoy](https://www.shadertoy.com) by Iñigo Quilez.
 
 ### To run / watch shader sketches 
-NB: since ruby-processing-2.6.11 glsl files are also __watched__, so you can edit the shader running with watch mode,
+NB: since ruby-processing-2.6.11 glsl files are also _watched_, so you can edit the shader running with watch mode,
 and it will automatically reload when you save your changes...
 ```bash
 # autorun all sketches