[question] "prettier-js is an available obsolete package."

[Fergus McDowall]

In Melpa it currently says that "prettier-js is an available obsolete package".

 Status: Available Obsolete from melpa -- Install
    Archive: melpa

    Version: 20180109.726
    Summary: Minor mode to format JS code on file save
   Homepage: https://github.com/prettier/prettier-emacs
   Keywords: convenience wp edit js 
Other versions: 20180109.726 (installed).

Why "obsolete"? What does this mean?