Update git-log and git-show documentation

Point at where the options not so frequently used are found.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-log.txt

@@ -16,7 +16,7 @@ Shows the commit logs.
 
 The command takes options applicable to the gitlink:git-rev-list[1]
 command to control what is shown and how, and options applicable to
-the gitlink:git-diff-tree[1] commands to control how the change
+the gitlink:git-diff-tree[1] commands to control how the changes
 each commit introduces are shown.
 
 This manual page describes only the most frequently used options.

Documentation/git-show.txt

@@ -25,6 +25,9 @@ with \--name-only).
 
 For plain blobs, it shows the plain contents.
 
+The command takes options applicable to the gitlink:git-diff-tree[1] command to
+control how the changes the commit introduces are shown.
+
 This manual page describes only the most frequently used options.