command-list.txt: add gitfaq to the list of guides

When 'gitfaq.txt' was added in 2149b6748f (docs: add a FAQ, 2020-03-30),
it was added to the Makefile but not to command-list.txt.

Add it there also, so that the new FAQ is listed in the output of
`git help --guides`.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

command-list.txt

@@ -197,6 +197,7 @@ gitcore-tutorial                        guide
 gitcvs-migration                        guide
 gitdiffcore                             guide
 giteveryday                             guide
+gitfaq                                  guide
 gitglossary                             guide
 githooks                                guide
 gitignore                               guide