feat:goctl model mongo add easy flag for easy declare. (#2073)

* fix:typo in readme.md

* feat:`goctl model mongo ` add `easy` flag to generate code with Auto generated CollectionName for easy declare.

* fix:`goctl api doc ` when referenced api file contains no route，will generate an empty markdown file.

* code: adjust code.

Co-authored-by: 虫子樱桃 <czyt@w.cn>

tools/goctl/api/docgen/doc.go

@@ -18,12 +18,14 @@ import (
 var markdownTemplate string
 
 func genDoc(api *spec.ApiSpec, dir, filename string) error {
+	if len(api.Service.Routes()) == 0 {
+		return nil
+	}
 	fp, _, err := util.MaybeCreateFile(dir, "", filename)
 	if err != nil {
 		return err
 	}
 	defer fp.Close()
-
 	var builder strings.Builder
 	for index, route := range api.Service.Routes() {
 		routeComment := route.JoinedDoc()