If you put that in, for example, `~/.vim/ftplugin/markdown.vim`, it will be used on all markdown files. (`../ftdetect/markdown.vim` controls how Vim determines

If you put that in, for example, `~/.vim/ftplugin/markdown.vim`, it will be used on all markdown files. (`../ftdetect/markdown.vim` controls how Vim determines that a file is markdown.)