INSTALL: git-merge no longer uses cpio

Since a64d7784e8 git merge doesn't use cpio
anymore, adapt the documentation.

Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

INSTALL

@@ -79,8 +79,8 @@ Issues of note:
 	- "perl" and POSIX-compliant shells are needed to use most of
 	  the barebone Porcelainish scripts.
 
-	- "cpio" is used by git-merge for saving and restoring the index,
-	  and by git-clone when doing a local (possibly hardlinked) clone.
+	- "cpio" is used by git-clone when doing a local (possibly
+	  hardlinked) clone.
 
  - Some platform specific issues are dealt with Makefile rules,
    but depending on your specific installation, you may not