added \label{sec:shell-scripts}

--- a/doc-src/Ref/introduction.tex	Wed Nov 29 16:47:38 1995 +0100
+++ b/doc-src/Ref/introduction.tex	Wed Nov 29 16:56:54 1995 +0100
@@ -220,7 +220,7 @@
   theory used in the last interactive proof.
 \end{warn}
 
-\section{Shell scripts}
+\section{Shell scripts}\label{sec:shell-scripts}
 \index{shell scripts|bold} The following files are distributed with
 Isabelle, and work under Unix$^{\rm TM}$.  They can be executed as commands
 to the Unix shell.  Some of them depend upon shell environment variables.