Adding documentation for "style" in version in software rendering list.

gpu/software_rendering_list/software_rendering_list.json

Index: gpu/software_rendering_list/software_rendering_list.json
===================================================================
--- gpu/software_rendering_list/software_rendering_list.json	(revision 140903)
+++ gpu/software_rendering_list/software_rendering_list.json	(working copy)
@@ -45,10 +45,14 @@
 // 20. "disabled" is a boolean. If it is present, the entry will be skipped.
 //     This can not be used in exceptions.
 //
-// VERSION includes "op" "number", and "number2".  "op" can be any of the
-// following values: "=", "<", "<=", ">", ">=", "any", "between".  "number2" is
-// only used if "op" is "between".  "number" is used for all "op" values except
-// "any". "number" and "number2" are in the format of x, x.x, x.x.x, etc.
+// VERSION includes "op", "style", "number", and "number2".  "op" can be any of
+// the following values: "=", "<", "<=", ">", ">=", "any", "between".  "style"
+// is optional and can be "lexical" or "numerical"; if it's not specified, it
+// defaults to "numerical".  "number2" is only used if "op" is "between".
+// "number" is used for all "op" values except "any". "number" and "number2"
+// are in the format of x, x.x, x.x.x, etc.
+// Only "driver_version" supports lexical style if the format is major.minor;
+// in that case, major is still numerical, but minor is lexical. 
 //
 // STRING includes "op" and "value".  "op" can be any of the following values:
 // "contains", "beginwith", "endwith", "=".  "value" is a string.