Documentation for git-shell

Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/git-shell.txt

+git-shell(1)
+============
+
+NAME
+----
+git-shell - Restricted login shell for GIT over SSH only
+
+
+SYNOPSIS
+--------
+'git-shell -c <command> <argument>'
+
+DESCRIPTION
+-----------
+This is meant to be used as a login shell for SSH accounts you want
+to restrict to GIT pull/push access only. It permits execution only
+of server-side GIT commands implementing the pull/push functionality.
+The commands can be executed only by the '-c' option; the shell is not
+interactive.
+
+Currently, only the `git-receive-pack` and `git-upload-pack` commands
+are permitted to be called, with a single required argument.
+
+Author
+------
+Written by Linus Torvalds <torvalds@osdl.org>
+
+Documentation
+--------------
+Documentation by Petr Baudis and the git-list <git@vger.kernel.org>.
+
+GIT
+---
+Part of the gitlink:git[7] suite
+

Documentation/git.txt

@@ -182,6 +182,9 @@ gitlink:git-receive-pack[1]::
 gitlink:git-send-pack[1]::
 	Pushes to a remote repository, intelligently.
 
+gitlink:git-shell[1]::
+	Restricted shell for GIT-only SSH access.
+
 gitlink:git-ssh-fetch[1]::
 	Pulls from a remote repository over ssh connection
 	Previously this command was known as git-ssh-pull.