git-rebase: Update --whitespace documentation

The parameters accepted by the --whitespace option of "git apply" have
changed over time, and the documentation for "git rebase" was out of
sync.  Remove the specific parameter list from the "git rebase"
documentation and simply point to the "git apply" documentation for
details, as is already done in the "git am" documentation.

Signed-off-by: Todd Zullinger <tmz@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-rebase.txt

@@ -243,7 +243,7 @@ OPTIONS
 	context exist they all must match.  By default no context is
 	ever ignored.
 
---whitespace=<nowarn|warn|error|error-all|strip>::
+--whitespace=<option>::
 	This flag is passed to the 'git-apply' program
 	(see linkgit:git-apply[1]) that applies the patch.
 	Incompatible with the --interactive option.