Interface Guidelines: migrate to docs/, use DocBookCSS.

DocBookCSS is a mostly-pure-CSS2 implementation of the DocBook standard.
Unlike DocBookXSL which relies on transforming the XML, it utilizes the
XML-styling features of modern web browsers to display the DocBook.

Its appearance still is a long way from the Haiku Book and Userguide, but
it looks (mostly) the same as the old DocBookXSL so we can stop using that.
Eventually we just need to make DocBookCSS use our styling.

build/jam/DocumentationRules

@@ -31,42 +31,3 @@ rule Man2Docs
 		Man2Doc $(target) : $(source) ;
 	}
 }
-
-rule Doc2HTML
-{
-	local source = [ FGristFiles $(1) ] ;
-	local target = [ FGristFiles $(2) ] ;
-	local xslsheet = $(3) ;
-	local basedir = [ FDirName $(HAIKU_DOCUMENTATION_DIR) $(4) ] ;
-	local paths = $(5) ;
-	local options = $(6) ;
-
-	if ! $(target) {
-		target = $(1:S=.html) ;
-	}
-
-	SEARCH on $(source) = $(SEARCH_SOURCE) ;
-
-	MakeLocate $(target) : $(basedir) ;
-	if $(2) {
-		XSLBASEDIR on $(target) = -stringparam base.dir \"$(basedir)/\" ;
-	}
-	XSLSHEET on $(target) = $(xslsheet) ;
-	XSLOPTIONS on $(target) = $(options) ;
-	if $(2) = "" {
-		XSLOUTPUT on $(target) = "-o "\"$(target:D=$(basedir))\" ;
-	}
-
-	XSLCATALOGS on $(target) = \" [ FDirName $(HAIKU_TOP) src documentation docbook-dtd catalog.xml ] [ FDirName $(HAIKU_TOP) src documentation docbook-xsl catalog.xml ] \" ;
-
-	Depends $(target) : $(source) <build>xsltproc ;
-	LocalDepends doc_files : $(target) ;
-	XSLPROCPATHS on $(target) = -path \" $(paths:J=\ ) \" ;
-	Doc2HTML1 $(target) : <build>xsltproc $(source) ;
-	LocalClean clean : $(target) ;
-}
-
-actions Doc2HTML1
-{
-	$(2[1]) --catalogs $(XSLCATALOGS) -xinclude $(XSLPROCPATHS) $(XSLBASEDIR) $(XSLOPTIONS) $(XSLOUTPUT) $(XSLSHEET) $(2[2-])
-}