Improve documentation page layout

It now has module list on the left and the main panel containing
a section for each module. Each section contains the navigable list
of the module's attributes, grouped by attribute's origin.

Test: Manual
Bug: 120512870
Change-Id: Ib62ef58c61daa88950f0934a70ba8ed16f433bf2

cmd/soong_build/main.go

@@ -75,8 +75,7 @@ func main() {
 	bootstrap.Main(ctx.Context, configuration, configuration.ConfigFileName, configuration.ProductVariablesFileName)
 
 	if docFile != "" {
-		err := writeDocs(ctx, docFile)
-		if err != nil {
+		if err := writeDocs(ctx, docFile); err != nil {
 			fmt.Fprintf(os.Stderr, "%s", err)
 			os.Exit(1)
 		}