There are some mikstakes(bugs?) to be fixed when
new_post() is executed to generate a new Rmarkdown file. The default front matter is as following:
--- layout: post title: new post date: `r Sys.time()` published: true tags: [example1, example2] ---
I have to change this yaml section as following then the post is available.
--- layout: post title: new post date: `r Sys.Date()` categories: example1, example2 ---
In addition, before the new blog post and article will be published, old
_site folder is better to be deleted.