[doc] more consistent use of vars in examples

incorporate some patches from macports package of lighttpd (thx)

doc/config/conf.d/auth.conf

@@ -11,7 +11,7 @@ server.modules += ( "mod_auth" )
 
 #server.modules += ( "mod_authn_file" )
 #auth.backend                 = "plain"
-#auth.backend.plain.userfile  = "/etc/lighttpd/lighttpd.user"
+#auth.backend.plain.userfile  = conf_dir + "/lighttpd.user"
 
 #server.modules += ( "mod_authn_ldap" )
 #auth.backend               = "ldap"

doc/config/conf.d/cgi.conf

@@ -41,7 +41,7 @@ cgi.assign                 = ( ".pl"  => "/usr/bin/perl",
 ## default: disable
 ##
 #cgi.x-sendfile = "enable"
-#cgi.x-sendfile-docroot = ( "/srv/www/html", "/srv/www/static" )
+#cgi.x-sendfile-docroot = ( server_root + "/html", server_root + "/static" )
 
 ##
 ## Local Redirect Response optimization

doc/config/conf.d/fastcgi.conf

@@ -125,7 +125,7 @@ server.modules += ( "mod_fastcgi" )
 #  )))
 #
 #server.chroot = "/srv/www"
-#server.document-root = "/servers/wwww.example.org/htdocs/"
+#server.document-root = "/servers/www.example.org/htdocs/"
 #
 
 ##

doc/config/conf.d/rrdtool.conf

@@ -15,7 +15,7 @@ rrdtool.binary             = "/usr/bin/rrdtool"
 ##
 ## Path to the rrdtool database. You can override this in conditionals.
 ##
-rrdtool.db-name            = "/var/lib/lighttpd/lighttpd.rrd"
+rrdtool.db-name            = home_dir + "/lighttpd.rrd"
 
 ##
 #######################################################################

doc/config/lighttpd.conf

@@ -388,7 +388,7 @@ static-file.exclude-extensions = ( ".php", ".pl", ".fcgi", ".scgi" )
 ## Format: <errorfile-prefix><status-code>.html
 ## -> ..../status-404.html for 'File not found'
 ##
-#server.errorfile-prefix    = "/srv/www/htdocs/errors/status-"
+#server.errorfile-prefix    = server_root + "/htdocs/errors/status-"
 
 ##
 ## mimetype mapping