help: move git-diff and git-reset to different groups

The third column in command-list.txt determines what group a common
command is printed in 'git help'.

"git reset" is currently in the "work on the current change (see also:
git help everyday)" group. While it's true that "git reset" can
manipulate the index and can be in this group, its unique
functionality is resetting HEAD, which should be the "grow, mark,
tweak history" group.

Moving it there will also avoid the confusion because both 'restore'
and 'reset' are in the same group, next to each other.

While looking at the 'group, mark, tweak history', I realize "git
diff" should not be there. All the commands in this group is about
_changing_ the commit history while "git diff" is a read-only
operation. It fits better in the "examine the history and state" group
(especially when "git status", its close friend, is already there).

This is what we have after the reorganization:

    work on the current change (see also: git help everyday)
       add       Add file contents to the index
       mv        Move or rename a file, a directory, or a symlink
       restore   Restore working tree files
       rm        Remove files from the working tree and from the index

    examine the history and state (see also: git help revisions)
       bisect    Use binary search to find the commit that introduced a bug
       diff      Show changes between commits, commit and working tree, etc
       grep      Print lines matching a pattern
       log       Show commit logs
       show      Show various types of objects
       status    Show the working tree status

    grow, mark and tweak your common history
       branch    List, create, or delete branches
       commit    Record changes to the repository
       merge     Join two or more development histories together
       rebase    Reapply commits on top of another base tip
       reset     Reset current HEAD to the specified state
       switch    Switch branches
       tag       Create, list, delete or verify a tag object signed with GPG

Signed-off-by: Nguyễn Thái Ngọc Duy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pclouds

command-list.txt

@@ -81,7 +81,7 @@ git-cvsimport                           foreignscminterface
 git-cvsserver                           foreignscminterface
 git-daemon                              synchingrepositories
 git-describe                            mainporcelain
-git-diff                                mainporcelain           history
+git-diff                                mainporcelain           info
 git-diff-files                          plumbinginterrogators
 git-diff-index                          plumbinginterrogators
 git-diff-tree                           plumbinginterrogators
@@ -150,7 +150,7 @@ git-repack                              ancillarymanipulators           complete
 git-replace                             ancillarymanipulators           complete
 git-request-pull                        foreignscminterface             complete
 git-rerere                              ancillaryinterrogators
-git-reset                               mainporcelain           worktree
+git-reset                               mainporcelain           history
 git-restore                             mainporcelain           worktree
 git-revert                              mainporcelain
 git-rev-list                            plumbinginterrogators