pack-protocol: fix first-want separator in the examples

When sending the "want" list, the capabilities list is separated from
the obj-id by a SP instead of NUL as in the ref advertisement. The
text is correct, but the examples wrongly show the separator as
NUL. Fix the example so it uses SP.
Signed-off-by: NCarlos Martín Nieto <cmn@elego.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/technical/pack-protocol.txt

@@ -351,7 +351,7 @@ Then the server will start sending its packfile data.
 A simple clone may look like this (with no 'have' lines):
 
 ----
-   C: 0054want 74730d410fcb6603ace96f1dc55ea6196122532d\0multi_ack \
+   C: 0054want 74730d410fcb6603ace96f1dc55ea6196122532d multi_ack \
      side-band-64k ofs-delta\n
    C: 0032want 7d1665144a3a975c05f1f43902ddaf084e784dbe\n
    C: 0032want 5a3f6be755bbb7deae50065988cbfa1ffa9ab68a\n
@@ -367,7 +367,7 @@ A simple clone may look like this (with no 'have' lines):
 An incremental update (fetch) response might look like this:
 
 ----
-   C: 0054want 74730d410fcb6603ace96f1dc55ea6196122532d\0multi_ack \
+   C: 0054want 74730d410fcb6603ace96f1dc55ea6196122532d multi_ack \
      side-band-64k ofs-delta\n
    C: 0032want 7d1665144a3a975c05f1f43902ddaf084e784dbe\n
    C: 0032want 5a3f6be755bbb7deae50065988cbfa1ffa9ab68a\n