removed 'concl is' pattern;

--- a/doc-src/IsarRef/syntax.tex	Sun May 07 00:22:05 2006 +0200
+++ b/doc-src/IsarRef/syntax.tex	Sun May 07 00:44:50 2006 +0200
@@ -399,7 +399,7 @@
 \begin{rail}
   termpat: '(' ('is' term +) ')'
   ;
-  proppat: '(' (('is' prop +) | 'concl' ('is' prop +) | ('is' prop +) 'concl' ('is' prop +)) ')'
+  proppat: '(' ('is' prop +) ')'
   ;
 \end{rail}