Fix the issue ref rendering for wiki (#28556) (#28559)

Backport #28556 by wxiaoguang

Fix #28526, regression of 
* #26365

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/markup/html.go

@@ -852,7 +852,9 @@ func fullIssuePatternProcessor(ctx *RenderContext, node *html.Node) {
 }
 
 func issueIndexPatternProcessor(ctx *RenderContext, node *html.Node) {
-	if ctx.Metas == nil || ctx.Metas["mode"] == "document" {
+	// FIXME: the use of "mode" is quite dirty and hacky, for example: what is a "document"? how should it be rendered?
+	// The "mode" approach should be refactored to some other more clear&reliable way.
+	if ctx.Metas == nil || (ctx.Metas["mode"] == "document" && !ctx.IsWiki) {
 		return
 	}
 	var (