Point out that for multiple AddLanguage directives with the
	same extension, the last one encountered dominates.  This is
	true of lots of directives, but this is the one on which we
	got a PR..

PR:	3570


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@83135 13f79535-47bb-0310-9956-ffa450edef68