Documentation: add a new man page for "git-help"

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-help.txt

@@ -0,0 +1,48 @@
+git-help(1)
+======
+
+NAME
+----
+git-help - display help information about git
+
+SYNOPSIS
+--------
+'git help' [-a|--all] [COMMAND]
+
+DESCRIPTION
+-----------
+
+With no options and no COMMAND given, the synopsis of the 'git'
+command and a list of the most commonly used git commands are printed
+on the standard output.
+
+If the option '--all' or '-a' is given, then all available commands are
+printed on the standard output.
+
+If a git command is named, a manual page for that command is brought
+up. The 'man' program is used by default for this purpose.
+
+Note that 'git --help ...' is identical as 'git help ...' because the
+former is internally converted into the latter.
+
+OPTIONS
+-------
+-a|--all::
+
+	Prints all the available commands on the standard output. This
+	option superseeds any other option.
+
+Author
+------
+Written by Junio C Hamano <gitster@pobox.com> and the git-list
+<git@vger.kernel.org>.
+
+Documentation
+-------------
+Initial documentation was part of the gitlink:git[7] man page.
+Christian Couder <chriscool@tuxfamily.org> extracted and rewrote it a
+little. Maintenance is done by the git-list <git@vger.kernel.org>.
+
+GIT
+---
+Part of the gitlink:git[7] suite

Documentation/git.txt

@@ -101,9 +101,9 @@ OPTIONS
 
 --help::
 	Prints the synopsis and a list of the most commonly used
-	commands.  If a git command is named this option will bring up
+	commands. If the option '--all' or '-a' is given then all
-	the man-page for that command. If the option '--all' or '-a' is
+	available commands are printed. If a git command is named this
-	given then all available commands are printed.
+	option will bring up the manual page for that command.
 
 --exec-path::
 	Path to wherever your core git programs are installed.

Makefile

@@ -1158,6 +1158,7 @@ check-docs::
 		case "$$how,$$cmd" in \
 		*,git-citool | \
 		*,git-gui | \
+		*,git-help | \
 		documented,gitattributes | \
 		documented,gitignore | \
 		documented,gitmodules | \

command-list.txt

@@ -46,6 +46,7 @@ git-get-tar-commit-id                   ancillaryinterrogators
 git-grep                                mainporcelain common
 git-gui                                 mainporcelain
 git-hash-object                         plumbingmanipulators
+git-help				ancillaryinterrogators
 git-http-fetch                          synchelpers
 git-http-push                           synchelpers
 git-imap-send                           foreignscminterface