Documentation/git-show.txt: include common diff options, like git-log.txt

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: moy

Documentation/git-show.txt

@@ -45,6 +45,15 @@ include::pretty-options.txt[]
 include::pretty-formats.txt[]
 
 
+COMMON DIFF OPTIONS
+-------------------
+
+:git-log: 1
+include::diff-options.txt[]
+
+include::diff-generate-patch.txt[]
+
+
 EXAMPLES
 --------