chore(announcement): change default announcement text (#1319)

* chore(announcement): change default announcement text for better clarity  

- Improve site announcement style for a more polished look
- Adjust default value to avoid unclear meaning with only repo or single link

Author: ILoveScratch2

internal/bootstrap/data/setting.go

@@ -100,7 +100,7 @@ func InitialSettings() []model.SettingItem {
 		//{Key: conf.ApiUrl, Value: "", Type: conf.TypeString, Group: model.SITE},
 		//{Key: conf.BasePath, Value: "", Type: conf.TypeString, Group: model.SITE},
 		{Key: conf.SiteTitle, Value: "OpenList", Type: conf.TypeString, Group: model.SITE},
-		{Key: conf.Announcement, Value: "### repo\nhttps://github.com/OpenListTeam/OpenList", Type: conf.TypeText, Group: model.SITE},
+		{Key: conf.Announcement, Value: "Welcome to the OpenList project!\nFor the latest updates, to contribute code, or to submit suggestions and issues, please visit our [project repository](https://github.com/OpenListTeam/OpenList).", Type: conf.TypeText, Group: model.SITE},
 		{Key: "pagination_type", Value: "all", Type: conf.TypeSelect, Options: "all,pagination,load_more,auto_load_more", Group: model.SITE},
 		{Key: "default_page_size", Value: "30", Type: conf.TypeNumber, Group: model.SITE},
 		{Key: conf.AllowIndexed, Value: "false", Type: conf.TypeBool, Group: model.SITE},