So package managers like npm, cargo, vim-plug etc. can show a warning message to the user. Message content would be the contents of the 'DEPRECATED' file in the projects root folder.
I understand that for example for npm there is the `npm deprecate` command, but I'm looking for a generic and simple way to do this.
Just noticed a VIM plugin I was using has been deprecated for a while, which caused some problems with VIM that I had to track down manually.