Updated Defining custom shaders (markdown)

Defining-custom-shaders.md

@@ -45,6 +45,7 @@ An example of a typical texture pack shader configuration is shown below:
         swampshaded: true
         waterbiomeshaded: true
         better-grass: false
+        grid-scale: 0
 
 The settings for the TexturePackHDShader include:
 
@@ -60,6 +61,8 @@ The settings for the TexturePackHDShader include:
 
 - _better-grass_ : This setting controls the option to render the sides of grass and snow blocks as done by the BetterGrass client mod.  If not defined, the value for _better-grass_ set in **configuration.txt** applies (which defaults to false).
 
+- _grid-scale_ : This setting, if defined and greater that zero, will result in a grid being drawn on the map tiles, with a white row and column of blocks every N tiles (so _grid-scale: 16_ would result in a grid with whitened blocks on every chunk border).  Since the block color is changed, the grid will conform to the contour of the map.
+
 An example of a typical topological shader configuration is shown below:
 
     shaders: