Document --colors in README

sfan5 · web-flow · commit 79121ade279a · 2016-08-28T15:58:06.000+02:00
diff --git a/README.rst b/README.rst
@@ -84,3 +84,5 @@ geometry:
 zoom:
     "Zoom" the image by using more than one pixel per node, e.g. ``--zoom 4``
 
+colors:
+    Forcefully set path to colors.txt file (it's autodetected otherwise), e.g. ``--colors ../minetest/mycolors.txt``
