Add the identifying header

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25352 a1c6a512-1295-4272-9138-f99709370657
diff --git a/manual/rockbox.tex b/manual/rockbox.tex
index 6533bdb..01e8401 100644
--- a/manual/rockbox.tex
+++ b/manual/rockbox.tex
@@ -1,3 +1,4 @@
+% $Id$ %
 \input{preamble.tex}
 
 \begin{document}