doc: add pilot and plugins documentation.

internal/gendoc.go

@@ -57,6 +57,11 @@ THIS FILE MUST NOT BE EDITED BY HAND
 	w.writeln()
 
 	for i, flat := range flats {
+		// TODO must be move into the flats creation.
+		if flat.Name == "experimental.plugins.<name>" || flat.Name == "TRAEFIK_EXPERIMENTAL_PLUGINS_<NAME>" {
+			continue
+		}
+
 		w.writeln("`" + prefix + strings.ReplaceAll(flat.Name, "[0]", "[n]") + "`:  ")
 		if flat.Default == "" {
 			w.writeln(flat.Description)