Documentation: describe -w/--web option to "git-help".

Also explain that "git instaweb" may use "web.browser" config
variable.

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

Documentation/git-help.txt

@@ -7,7 +7,7 @@ git-help - display help information about git
 
 SYNOPSIS
 --------
-'git help' [-a|--all|-i|--info] [COMMAND]
+'git help' [-a|--all|-i|--info|-w|--web] [COMMAND]
 
 DESCRIPTION
 -----------
@@ -29,14 +29,31 @@ 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.
 
 -i|--info::
 	Use the 'info' program to display the manual page, instead of
 	the 'man' program that is used by default.
 
+-w|--web::
+	Use a web browser to display the HTML manual page, instead of
+	the 'man' program that is used by default.
++
+The web browser can be specified using the configuration variable
+'help.browser', or 'web.browser' if the former is not set. If none of
+these config variables is set, the 'git-browse-help' script (called by
+'git-help') will pick a suitable default.
++
+You can explicitly provide a full path to your prefered browser by
+setting the configuration variable 'browser.<tool>.path'. For example,
+you can configure the absolute path to firefox by setting
+'browser.firefox.path'. Otherwise, 'git-browse-help' assumes the tool
+is available in PATH.
++
+Note that the script tries, as much as possible, to display the HTML
+page in a new tab on an already opened browser.
+
 Author
 ------
 Written by Junio C Hamano <gitster@pobox.com> and the git-list

Documentation/git-instaweb.txt

@@ -71,6 +71,9 @@ You may specify configuration in your .git/config
 
 -----------------------------------------------------------------------
 
+If the configuration variable 'instaweb.browser' is not set,
+'web.browser' will be used instead if it is defined.
+
 Author
 ------
 Written by Eric Wong <normalperson@yhbt.net>