command-list.txt: remove 'sparse-index' from main help

Ever since 'git sparse-checkout' was introduced [1] it is included in
'git --help' in the section "work on the current change" along with
the commands 'add', 'mv', 'restore', and 'rm'.  It clearly doesn't
belong to that group, moreover it can't be considered such a common
command to belong to 'git --help' in the first place, so remove it
from there.

[1] 94c0956 (sparse-checkout: create builtin with 'list'
                subcommand, 2019-11-21)

Signed-off-by: SZEDER Gábor <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: szeder

command-list.txt

@@ -168,7 +168,7 @@ git-show-index                          plumbinginterrogators
 git-show-ref                            plumbinginterrogators
 git-sh-i18n                             purehelpers
 git-sh-setup                            purehelpers
-git-sparse-checkout                     mainporcelain           worktree
+git-sparse-checkout                     mainporcelain
 git-stash                               mainporcelain
 git-stage                                                               complete
 git-status                              mainporcelain           info