Use body text color in repository files table links (#20386)

Use body text color in for links in the repository files table
Issue/PR links (`.ref-issue`) will not be affected, as seen in other git services.

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

modules/markup/html.go

@@ -1176,7 +1176,7 @@ func genDefaultLinkProcessor(defaultLink string) processor {
 		node.DataAtom = atom.A
 		node.Attr = []html.Attribute{
 			{Key: "href", Val: defaultLink},
-			{Key: "class", Val: "default-link"},
+			{Key: "class", Val: "default-link muted"},
 		}
 		node.FirstChild, node.LastChild = ch, ch
 	}