gitweb: Add example of config file and how to generate projects list to gitweb/INSTALL

Add simple example of config file (turning on and allowing override of
a few %features). Also example config file and script to generate list
of projects in a format that can be used as GITWEB_LIST / $projects_list.
Signed-off-by: NJakub Narebski <jnareb@gmail.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

gitweb/INSTALL

@@ -103,9 +103,25 @@ for gitweb (in gitweb/README).
 
   See the top of gitweb.perl file for examples of customizable options.
 
+Config file example
+~~~~~~~~~~~~~~~~~~~
 
-Gitweb repositories:
---------------------
+To enable blame, pickaxe search, and snapshot support, while allowing
+individual projects to turn them off, put the following in your
+GITWEB_CONFIG file:
+
+	$feature{'blame'}{'default'} = [1];
+	$feature{'blame'}{'override'} = 1;
+
+	$feature{'pickaxe'}{'default'} = [1];
+	$feature{'pickaxe'}{'override'} = 1;
+
+	$feature{'snapshot'}{'default'} = ['x-gzip', 'gz', 'gzip'];
+	$feature{'snapshot'}{'override'} = 1;
+
+
+Gitweb repositories
+-------------------
 
 - By default all git repositories under projectroot are visible and
   available to gitweb. List of projects is generated by default by
@@ -139,6 +155,31 @@ Gitweb repositories:
   show repository only if this file exists in its object database
   (if directory has the magic file $export_ok).
 
+Generating projects list using gitweb
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+We assume that GITWEB_CONFIG has its default Makefile value, namely
+gitweb_config.perl. Put the following in gitweb_make_index.perl file:
+
+	$GITWEB_CONFIG = "gitweb_config.perl";
+	do $GITWEB_CONFIG if -e $GITWEB_CONFIG;
+
+	$projects_list = $projectroot;
+
+Then create the following script to get list of project in the format
+suitable for GITWEB_LIST build configuration variable (or
+$projects_list variable in gitweb config):
+
+	#!/bin/sh
+
+	export GITWEB_CONFIG="gitweb_make_index.perl"
+	export GATEWAY_INTERFACE="CGI/1.1"
+	export HTTP_ACCEPT="*/*"
+	export REQUEST_METHOD="GET"
+	export QUERY_STRING="a=project_index"
+
+	perl -- /var/www/cgi-bin/gitweb.cgi
+
 
 Requirements
 ------------