color: don't mention internal function in docstring stable

color: don't mention internal function in docstring

The render_text function actually never existed, the docstring
probably meant the render_effects function instead.

--- a/hgext/color.py	Sun Mar 13 16:18:46 2011 +0100
+++ b/hgext/color.py	Mon Mar 14 13:54:25 2011 +0100
@@ -26,8 +26,7 @@
 
 Other effects in addition to color, like bold and underlined text, are
 also available. Effects are rendered with the ECMA-48 SGR control
-function (aka ANSI escape codes). This module also provides the
-render_text function, which can be used to add effects to any text.
+function (aka ANSI escape codes).
 
 Default effects may be overridden from your configuration file::