doc: fix naming of response-end-pkt

doc: fix naming of response-end-pkt

Git Protocol version 2[1] defines 0002 as a Message Packet that indicates
the end of a response for stateless connections.

Change the naming of the 0002 Packet to 'Response End' to match the
parsing introduced in Wireshark's MR !1922 for consistency. A subsequent
MR in Wireshark will address additional mismatches.

[1] kernel.org/pub/software/scm/git/docs/technical/protocol-v2.html
[2] gitlab.com/wireshark/wireshark/-/merge_requests/1922

Signed-off-by: Joey Salazar <jgsal@protonmail.com>
Reviewed-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>