doc: remove non pure ASCII characters

Non ASCII characters may be handled by publishing chains, but right
now, nothing indicates the encoding of files. Moreover, non ASCII
source strings upset the localization toolchain.

Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-clone.txt

@@ -262,9 +262,9 @@ or `--mirror` is given)
 	All submodules which are cloned will be shallow with a depth of 1.
 
 --[no-]remote-submodules::
-	All submodules which are cloned will use the status of the submodule’s
+	All submodules which are cloned will use the status of the submodule's
 	remote-tracking branch to update the submodule, rather than the
-	superproject’s recorded SHA-1. Equivalent to passing `--remote` to
+	superproject's recorded SHA-1. Equivalent to passing `--remote` to
 	`git submodule update`.
 
 --separate-git-dir=<git dir>::