Fix markup error introduced in r9626.

[originally from svn r9627] [r9626 == 92fc25c6cd]
2012-08-26 09:50:57 +00:00 · 2012-08-26 09:50:57 +00:00 · 85c95e30e4
--- a/doc/errors.but
+++ b/doc/errors.but
@ -1,4 +1,4 @@
-s\define{versioniderrors} \versionid $Id$
+\define{versioniderrors} \versionid $Id$

 \C{errors} Common \i{error messages}